Worcester Bosch Greenstar 2000 Fault codes & diagnostics

276 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Combi Natural Gas 25-30 kW 2020-present

This boiler uses LED flash patterns

Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
15 Emergency 205 High 16 Medium 40 Low

All 276 documented codes

Tap any card for details

Green/Red - blinking

Your boiler is notifying you that it is currently running, but it has detected a minor inconsistency in how it is circulating water around your system.

Low Engineer only £90-180

Parts commonly replaced

  • Central Heating Pump
  • System Filter
  • Pressure Sensor

Related codes

Red - blinking

Your boiler has detected that water is failing to circulate correctly, so it has temporarily shut down its internal pump to prevent internal damage.

High Engineer only £150-300

Parts commonly replaced

  • Central heating pump
  • PCB
  • NTC thermistor

Related codes

0-A1

Your boiler has been manually switched off or into a service mode and simply needs to be restarted or reset to resume normal operation.

Low DIY-safe £0-80

What to check first

  1. Locate the main Power/Reset button on the boiler control panel.
  2. Press and hold the Reset button for 3 to 5 seconds.
  3. Wait for the boiler to complete its startup sequence and return to the home screen.

Related codes

0-A2

Your boiler is operating in a service mode used for manual testing and checking heating temperatures.

Low DIY-safe £0-80

What to check first

  1. Check if the service button or chimney sweep mode has been accidentally activated.
  2. Turn the boiler off and back on at the main power switch to reset the control panel.
  3. Adjust the temperature dial or digital controls to exit the manual override menu.

Related codes

1-d4

Your boiler is having trouble communicating with your solar water heating system, which means the solar panels may not be contributing to your hot water at the moment.

Medium Engineer only £150-300

Parts commonly replaced

  • Solar sensor
  • Solar control module
  • Wiring loom
4-A1

Your boiler is currently running a programmed air removal sequence to clear bubbles from the heating pipes, which is a normal setup process rather than a mechanical failure.

Low DIY-safe

What to check first

  1. Wait approximately 10 to 15 minutes for the automated venting cycle to complete naturally.
  2. Check that your radiator valves are open to help the air circulate out of the system.
  3. If the code persists, restart the boiler by holding the reset button for 3 seconds.

Related codes

4-A2

Your boiler is performing a routine initial setup or maintenance check to fill the internal condensate trap with water and is not actually at fault.

Low DIY-safe

What to check first

  1. Wait approximately 15 minutes for the program to complete automatically
  2. Ensure your thermostat is calling for heat to allow the boiler to cycle through the process
  3. If the code persists for over 30 minutes, restart the boiler by pressing the reset button

Related codes

4-A4

Your boiler is simply letting you know that it is due for its routine annual service based on how long it has been running.

Low Engineer only £80-120

Parts commonly replaced

  • Service kit (seals and electrodes)
  • Burner gasket

Related codes

4-A5

Your boiler is simply letting you know that it has reached its scheduled running time and is now due for a routine service.

Low Engineer only £80-120

Parts commonly replaced

  • Service kit (seals and electrodes)
4-A6

Your boiler is simply reminding you that its scheduled service is due based on the time interval set by your engineer.

Low Engineer only £80-120

Parts commonly replaced

  • Service kit (washers and seals)
Showing 11–20 of 276
4-b1

Your boiler is simply indicating whether its internal weather-monitoring feature is currently turned on or off.

Low DIY-safe

What to check first

  1. Locate the boiler's control panel
  2. Navigate to the secondary settings menu
  3. Enable or disable the 'Weather Compensation' setting based on your preference
4-b2

Your boiler has automatically switched off the heating because it thinks the weather outside is warm enough that you don't need it.

Low DIY-safe £0-60

What to check first

  1. Locate the heating temperature dial or settings menu on your boiler control panel.
  2. Adjust the 'Summer/Winter' threshold setting if you want the heating to come on at higher outdoor temperatures.
  3. Check your external weather compensation sensor for any obstructions or dirt if the reading seems incorrect.

Parts commonly replaced

  • Outside weather sensor
  • Wiring connector

Related codes

4-b3

Your boiler is notifying you that the settings for its automatic outdoor temperature sensors are incorrectly configured or out of their allowed range.

Low DIY-safe £0-80

What to check first

  1. Navigate to the service menu on the control panel
  2. Locate the weather compensation settings
  3. Adjust the heating curve end point to a value between 20°C and 90°C
  4. Press the reset button to clear the notification

Related codes

4-b4

Your boiler is notifying you that there is a settings error or a communication issue with your outdoor temperature sensor or heating curve configuration.

Low DIY-safe £60-120

What to check first

  1. Check that the outdoor sensor is not obstructed or damaged
  2. Switch the boiler off and back on to see if the error clears
  3. Enter the menu to reset the heating curve values if you have recently changed them

Parts commonly replaced

  • Outdoor weather compensator sensor
  • Sensor wiring harness
4-b5

Your boiler is notifying you that its internal protection against freezing has been activated or deactivated, which is a normal safety monitoring function.

Low DIY-safe

What to check first

  1. Check your home temperature is above 5°C
  2. Ensure the boiler power supply remains switched on
  3. Monitor the display to see if the code clears once the unit reaches a safe temperature
4-b6

Your boiler has detected that the internal water temperature is very low and has activated its built-in frost protection mode to prevent freezing.

Low DIY-safe £0-80

What to check first

  1. Ensure the boiler's electrical power remains switched on
  2. Check that the room thermostat or programmer is calling for heat
  3. Allow the boiler to run its automatic anti-freeze cycle until the temperature rises
  4. Ensure any external pipework is properly insulated with lagging

Parts commonly replaced

  • External pipe insulation
  • NTC Temperature Sensor
4-E2

Your boiler has detected a tempereature sensor reading that is outside of its normal range, likely due to a faulty sensor or a communication error between parts.

High Engineer only £120-£210

Parts commonly replaced

  • Flow temperature sensor
  • NTC thermistor
  • Wiring harness

Related codes

4-F1

Your boiler has experienced a memory or software error and needs to be restarted to restore its original settings.

High DIY-safe £0-120

What to check first

  1. Locate the 'Reset' button on the boiler control panel.
  2. Press and hold the Reset button for 3 to 5 seconds.
  3. Wait for the boiler to complete its restart sequence and check if the display returns to normal.

Parts commonly replaced

  • None (Software reset)
  • Circuit Board (PCB)

Related codes

4-F2

Your boiler has likely overheated, causing it to shut down as a safety precaution to prevent damage.

High DIY-safe £100-280

What to check first

  1. Check that your radiator valves are open to allow water to flow.
  2. Check the boiler pressure gauge and top up to 1.5 bar if it is too low.
  3. Press and hold the 'Reset' button on the front of the boiler for three seconds.

Parts commonly replaced

  • Overheat Thermostat
  • Circulating Pump
  • Temperature Sensor (NTC thermistor)

Related codes

5-A1

Your boiler has detected that the water temperature has exceeded the maximum safe limit, causing it to shut down to prevent damage.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves (TRVs) are turned to the maximum setting.
  2. Ensure the boiler pressure is within the green zone (usually 1 to 1.5 bar).
  3. Check if the magnetic system filter is blocked or needs cleaning.

Parts commonly replaced

  • Circulation pump
  • Temperature thermistor (NTC sensor)
  • Main Heat Exchanger (if scaled or blocked)

Related codes

Showing 21–30 of 276
5-A2

Your boiler has detected that the hot water temperature has exceeded its maximum safe limit and has shut down as a precaution.

Medium Engineer only £120-280

Parts commonly replaced

  • DHW Temperature Sensor (NTC thermistor)
  • Plate Heat Exchanger
  • Main PCB

Related codes

5-A3

Your boiler is struggling to run at its lowest power setting, which can cause it to shut down for safety while heating your home or water.

Medium Engineer only £120-280

Parts commonly replaced

  • Gas Valve
  • Fan
  • Control PCB

Related codes

6-t1

Your boiler is undergoing a diagnostic test where it attempts to spark repeatedly without releasing gas to check the ignition system.

Low DIY-safe £0-120

What to check first

  1. Wait for the testing cycle to complete automatically
  2. Turn the boiler off and back on again to reset the sequence
  3. If the code persists and the boiler won't fire, contact a professional

Parts commonly replaced

  • None (Software mode)
  • Ignition Electrode
  • Control Box

Related codes

6-t2

Your boiler's fan is running continuously even though the heating is not trying to start, which is often caused by a communication error between the internal computer and the fan motor.

High Engineer only £250-£450

Parts commonly replaced

  • Fan Assembly
  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

6-t3

Your boiler is staying on and circulating water continuously because it thinks it is in a permanent cooling-down phase, even when it isn't needed.

Medium Engineer only £120-£350

Parts commonly replaced

  • Main PCB
  • Pump unit
  • NTC Sensor

Related codes

6-t5

Your boiler is stuck in hot water mode, meaning your taps will work but your radiators will fail to heat up.

Medium DIY-safe £160-280

What to check first

  1. Turn the boiler power off at the fused spur switch for 30 seconds and turn it back on to reset the valve position.
  2. Press the 'Reset' button on the boiler control panel.
  3. Ensure your room thermostat is calling for heat to encourage the valve to switch.

Parts commonly replaced

  • Diverter Valve Actuator Motor
  • Complete 3-Way Diverter Valve Assembly

Related codes

6-tA

Your boiler is having trouble detecting the flame it needs to stay lit, which is preventing the system from heating your home or water.

High Engineer only £120-280

Parts commonly replaced

  • Ionisation electrode
  • Flame sensing lead
  • Printed Circuit Board (PCB)

Related codes

6-tb

Your boiler is currently running a self-diagnostic test to check the burner's performance across its full power range.

Low DIY-safe

What to check first

  1. Wait for approximately 15 minutes for the test to complete automatically
  2. Monitor the display to see if it returns to the normal temperature reading
  3. If the code persists for over an hour, try restarting the boiler using the reset button
Showing 31–40 of 276
202

Your boiler is taking a short rest between heating cycles to prevent rapid stop-start wearing, which is a normal protective feature ensuring it doesn't overheat.

Low Engineer only
203

Your boiler is perfectly healthy and is simply waiting for you to turn on a tap or adjust your heating thermostat.

Low DIY-safe

What to check first

  1. Check that your room thermostat or heating programmer is set to 'on'
  2. Ensure the hot water tap is fully open if you are testing for hot water

Related codes

204

Your boiler has detected that the water inside the unit is getting too hot, so it has safely shut itself down to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Central Heating Pump
  • Plate Heat Exchanger
208

Your boiler has been accidentally switched into a specific testing mode used by engineers to check emissions, which prevents it from heating your home normally.

Low DIY-safe

What to check first

  1. Locate the chimney sweep button on your boiler's control panel (often marked with a chimney icon).
  2. Press the button once to exit the testing mode.
  3. Wait for the display to return to its normal temperature reading and check if the boiler resumes standard operation.

Related codes

212

Your boiler is shutting down because it is heating up much faster than it can circulate the water, which often points to a blockage or a pump issue.

High Engineer only £150-300

Parts commonly replaced

  • Central heating pump
  • System filter
  • Diverter valve

Related codes

213

Your boiler has sensed that heat is not moving through the system properly, causing the water going out to be much hotter than the water coming back in.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the boiler pressure is between 1 and 1.5 bar
  3. Bleed all radiators to remove trapped air

Parts commonly replaced

  • Circulation Pump
  • Flow/Return Thermistors
  • Main Heat Exchanger (Descaling)

Related codes

214

Your boiler has stopped working because it detected a problem with the internal fan that pushes exhaust gases out of your home.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

215

Your boiler has detected that the internal fan responsible for venting exhaust gases failed to start properly during its initial safety check.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

223

Your boiler has lost its connection to an internal temperature sensor, meaning it cannot tell how hot the water is and has shut down for safety.

High Engineer only £90-180

Parts commonly replaced

  • NTC Thermistor
  • Wiring Harness
  • Control Board

Related codes

224

Your boiler has detected that it is running too hot and has automatically shut itself down to prevent any damage or safety issues.

High Engineer only £150-300

Parts commonly replaced

  • NTC Sensor
  • Heat Exchanger
  • Pump
  • Diverter Valve

Related codes

Showing 41–50 of 276
227

Your boiler is trying to start, but it cannot detect a flame, so it has safely shut itself down to prevent gas from building up.

High Engineer only £150-350

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

228

Your boiler has detected a signal that suggests a flame is present when it should not be, leading the system to shut down for safety reasons.

Emergency Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Flame sensing electrode
  • Gas valve

Related codes

229

Your boiler has stopped heating because the flame inside went out while it was trying to run.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board

Related codes

232

Your boiler has been told to stop running by an external device, such as a smart thermostat or a frost protection controller.

Medium Engineer only £100-200

Parts commonly replaced

  • External heating controller
  • Smart thermostat
  • Wiring centre

Related codes

233

Your boiler has lost communication with its internal computer, meaning it cannot safely operate or control your heating and hot water.

High Engineer only £200-400

Parts commonly replaced

  • Main printed circuit board (PCB)
  • HIM (Heating identification module)

Related codes

234

Your boiler has detected an issue with the control system that manages the gas supply, so it has safely shut down to prevent any risk.

High Engineer only £180-300

Parts commonly replaced

  • Gas valve
  • Wiring harness
  • Printed Circuit Board (PCB)

Related codes

235

Your boiler's internal computer is confused because its internal identification settings do not match the specific components installed, causing it to lock itself to prevent incorrect operation.

High Engineer only £120-250

Parts commonly replaced

  • Main Control Unit (PCB)
  • Coding Plug

Related codes

237

Your boiler has detected an internal communication error and has safely shut down to prevent potential damage.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

238

Your boiler's internal computer is experiencing a major communication error and is unable to safely control the system.

High Engineer only £250-450

Parts commonly replaced

  • Main Control Board
  • Wiring Harness

Related codes

240

Your boiler has lost communication with its internal temperature sensor, meaning it cannot monitor heat levels safely and has shut down.

High Engineer only £100-180

Parts commonly replaced

  • Flow/Return NTC Sensor
  • Wiring Harness
  • Circuit Board

Related codes

Showing 51–60 of 276
241

Your boiler has lost its connection to its internal temperature sensor, meaning it cannot accurately monitor how hot the water is and has stopped working as a safety precaution.

High Engineer only £90-180

Parts commonly replaced

  • Flow NTC sensor
  • Wiring harness
  • Return NTC sensor

Related codes

242

Your boiler's main control unit is experiencing a communication error or electrical glitch that is preventing it from operating correctly.

High Engineer only £180-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

244

Your boiler's main control computer is experiencing a temporary glitch or internal error, which has caused it to stop working for safety reasons.

High Engineer only £150-350

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Control unit

Related codes

245

Your boiler has detected an internal communication error and has safely shut down to prevent potential damage.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

246

Your boiler's internal computer is experiencing a communication error and cannot safely manage the heating or hot water systems.

High Engineer only £250-450

Parts commonly replaced

  • Main printed circuit board
  • Wiring harness

Related codes

247

Your boiler's internal computer is experiencing a communication error or technical failure, preventing it from operating correctly.

High Engineer only £250-450

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Wiring harness

Related codes

248

Your boiler has encountered a technical issue with its internal memory or electronic circuit board, which has stopped it from running safely.

High Engineer only £250-£550

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Control Unit

Related codes

249

Your boiler's computer system has encountered a logic error and needs to be restarted to clear the fault.

High DIY-safe £120-250

What to check first

  1. Locate your boiler's reset button
  2. Press and hold the reset button for 3 to 5 seconds
  3. Wait for the boiler to reboot and check if the error code clears

Parts commonly replaced

  • Main control board (PCB)

Related codes

250

Your boiler's computer system has encountered an internal error and cannot operate correctly.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

251

Your boiler's computer is having a internal memory error that is preventing it from starting up safely.

High Engineer only £200-400

Parts commonly replaced

  • Main printed circuit board (PCB)

Related codes

Showing 61–70 of 276
252

Your boiler's internal computer is experiencing a temporary processing error that is preventing it from starting up correctly.

High Engineer only £120-250

Parts commonly replaced

  • Main Control Board

Related codes

253

Your boiler’s internal computer is experiencing a memory error and cannot safely operate its recovery systems.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

254

Your boiler's computer memory has detected an internal data error, meaning the control system is confused and cannot safely operate the boiler.

High Engineer only £200-400

Parts commonly replaced

  • Main PCB
256

Your boiler's internal computer is experiencing a communication error and has decided to shut down to prevent potential damage.

High Engineer only £250-450

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Wiring harness

Related codes

257

Your boiler's main control computer is experiencing a temporary glitch or internal error, which has caused it to pause its normal operation as a safety precaution.

High Engineer only £200-450

Parts commonly replaced

  • Main printed circuit board (PCB)

Related codes

258

Your boiler's computer system has encountered an internal error and has temporarily shut itself down to prevent any further issues.

High Engineer only £180-350

Parts commonly replaced

  • Main PCB

Related codes

259

Your boiler's computer is struggling to read internal electronic signals, which has caused it to stop working to ensure safety.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
262

Your boiler's computer system has encountered an internal glitch and needs to be restarted or reset by a professional.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

263

Your boiler's computer is experiencing a temporary software confusion which is preventing it from starting up correctly.

High Engineer only £120-250

Parts commonly replaced

  • Printed circuit board (PCB)

Related codes

264

Your boiler is struggling to breathe properly, meaning it cannot safely clear exhaust gases and has shut down to protect your home.

High Engineer only £150-300

Parts commonly replaced

  • Fan assembly
  • Flue debris/blockage
  • Air pressure switch

Related codes

Showing 71–80 of 276
265

Your boiler is currently heating the water faster than your radiators or taps can use it, causing it to throttle down or pause to prevent overheating.

Low Engineer only £120-250

Parts commonly replaced

  • NTC thermistor
  • Primary flow sensor
  • System filter
268

Your boiler has performed an internal safety test of its electronic controls and is currently waiting for you to restart the system to see if the error clears.

Medium DIY-safe £120-250

What to check first

  1. Switch off the boiler at the fused spur or mains power switch
  2. Wait for 60 seconds
  3. Turn the power back on to allow the boiler to perform a fresh self-test

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

269

Your boiler is failing to detect a flame, which means it has safely shut itself down to prevent gas from building up.

Emergency Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

270

Your boiler is currently booting up, which is a normal process while it checks its systems before starting to heat your home.

Low DIY-safe

What to check first

  1. Wait 2-5 minutes for the boiler to complete its start-up sequence
  2. If the code does not clear, switch the boiler off at the fused spur
  3. Wait 30 seconds and switch it back on to force a re-start
273

Your boiler has stopped working because it cannot safely start the internal fire that heats your water.

High Engineer only £150-300

Parts commonly replaced

  • Fan unit
  • Wiring harness
  • Printed Circuit Board

Related codes

275

Your boiler is currently stuck in a diagnostic testing mode rather than operating normally to provide heating or hot water.

Medium Engineer only £100-250

Parts commonly replaced

  • Main control board
  • Interface module

Related codes

281

Your boiler is struggling to push water around your heating system because the internal water pressure is too low or the pump is failing to detect movement.

High DIY-safe £120-250

What to check first

  1. Check your boiler pressure gauge; if it is below 1 bar, locate the filling loop and add water until it reaches 1.5 bar
  2. Turn the boiler off at the fused spur for 30 seconds and then switch it back on to reset the system
  3. Ensure all radiator valves are fully open to allow for proper flow

Parts commonly replaced

  • Central heating pump
  • Pressure sensor
  • Expansion vessel

Related codes

282

Your boiler is struggling to move water around the system because the pump isn't detecting enough pressure when it starts up.

High DIY-safe £180-350

What to check first

  1. Check the pressure gauge on the front of the boiler
  2. If the pressure is below 1 bar, use the filling link to top it up to 1.5 bar
  3. Bleed any trapped air from your radiators
  4. Restart the boiler using the reset button

Parts commonly replaced

  • Circulation pump
  • Water pressure sensor
  • Expansion vessel charge

Related codes

283

Your boiler is currently just in the process of lighting the flame to begin heating your water or radiators.

Low Engineer only
284

Your boiler is having difficulty communicating with the system that manages the essential mix of gas and air needed for safe ignition.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • Wiring harness
  • Main PCB

Related codes

Showing 81–90 of 276
285

Your boiler has stopped working because the water returning from your radiators is too hot, which usually means the heat isn't being released into your home correctly.

High DIY-safe £100-£250

What to check first

  1. Check that at least two or three radiators have their valves fully open
  2. Ensure your Thermostatic Radiator Valves (TRVs) are not all turned to the lowest setting
  3. Check your external system pump is running if you have a separate one

Parts commonly replaced

  • Circulation Pump
  • Return Temperature Sensor (NTC)
  • Bypass Valve

Related codes

305

Your boiler is temporarily pausing to prevent overheating while it manages your hot water supply, which is a normal part of its internal self-regulation.

Low Engineer only
306

Your boiler has detected that the flame is still burning even though it has told the gas supply to shut off.

Emergency Engineer only £150-300

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

323

Your boiler's internal computer is failing to communicate correctly with its external controls, preventing your heating or hot water from turning on.

High Engineer only £150-300

Parts commonly replaced

  • Main PCB
  • Wiring harness
  • External thermostat/programmer
328

Your boiler has briefly lost power, likely due to a minor power cut or a loose plug connection.

Low DIY-safe

What to check first

  1. Check that your boiler's power switch is firmly in the 'on' position.
  2. Check your household consumer unit to ensure the circuit breaker for the heating system hasn't tripped.
  3. Ensure the plug socket supplying the boiler is fully pushed in if it is not hard-wired.

Parts commonly replaced

  • None - usually resolves via power reset

Related codes

341

Your boiler is heating up much faster than it should, which has caused it to automatically shut down to prevent potential damage from overheating.

High Engineer only £150-350

Parts commonly replaced

  • Pump
  • Diverter valve
  • Heat exchanger
  • System filter
342

Your boiler is heating the water much faster than it is able to move it away, causing the system to stop as a safety precaution to prevent overheating.

High Engineer only £150-300

Parts commonly replaced

  • Diverter valve
  • Primary heat exchanger
  • Pump
347

Your boiler has stopped because the water returning from your radiators is hotter than the water leaving the boiler, which usually means the internal sensors are confused or the water is flowing the wrong way.

High Engineer only £120-280

Parts commonly replaced

  • Flow temperature NTC sensor
  • Return temperature NTC sensor
  • Circulation pump

Related codes

350

Your boiler has lost its ability to accurately measure the temperature of the water flowing through the heating system because one of its internal sensors is sending a faulty electrical signal.

High Engineer only £120-220

Parts commonly replaced

  • NTC flow temperature sensor
  • Wiring harness

Related codes

351

Your boiler has lost its ability to measure the temperature of the water flowing through the system, so it has purposefully stopped working to prevent overheating.

High Engineer only £120-200

Parts commonly replaced

  • NTC flow temperature sensor
  • Wiring harness

Related codes

Showing 91–100 of 276
353

Your boiler has detected an internal error during its automatic safety check and has locked itself down to prevent operation.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

354

Your boiler has detected an internal software or safety check failure and has shut down to prevent unsafe operation.

High Engineer only £180-350

Parts commonly replaced

  • Main PCB
  • Wiring harness

Related codes

356

Your boiler is struggling because the electricity supply it is receiving is weaker than it needs to operate reliably.

High Engineer only £100-250

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
  • External power supply/fused spur

Related codes

357

Your boiler is currently running a brief automatic safety check of its internal air and exhaust system before it attempts to fire up.

Low Engineer only
360

Your boiler's internal computer is struggling to recognise the electronic identification chip that stores its specific settings.

High Engineer only £150-300

Parts commonly replaced

  • Code plug
  • Printed Circuit Board (PCB)

Related codes

362

Your boiler's computer is having trouble recognising its own internal settings and requires a professional to reset or replace the electronic control unit.

High Engineer only £250-450

Parts commonly replaced

  • Key coding plug
  • Main printed circuit board (PCB)

Related codes

363

Your boiler is struggling to confirm that the burner flame has safely extinguished before attempting to restart.

High Engineer only £150-250

Parts commonly replaced

  • Ionisation electrode
  • Printed circuit board (PCB)

Related codes

364

Your boiler has detected that an internal valve responsible for controlling gas flow is not sealing properly, meaning it cannot operate safely.

Emergency Engineer only £180-300

Parts commonly replaced

  • Gas valve assembly

Related codes

365

Your boiler has detected an internal issue where a component responsible for controlling the fuel supply is failing to shut properly, preventing the system from operating safely.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve assembly
  • Wiring harness

Related codes

Showing 101–110 of 276
522

Your boiler is currently performing a self-diagnostic check on its internal temperature sensors to ensure they are reading accurately.

Low DIY-safe £100-220

What to check first

  1. Wait for 5-10 minutes as this is often a temporary automated test.
  2. If the code persists, try restarting the boiler using the reset button.
  3. Check that your radiator valves are open to allow water to circulate freely.

Parts commonly replaced

  • Flow NTC sensor
  • Return NTC sensor

Related codes

604

Your boiler's electronic brain is having trouble communicating with the burner, meaning your heating and hot water have stopped working for safety reasons.

High Engineer only £200-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
  • Ignition lead

Related codes

810

Your boiler is failing to detect or trigger the heating process required to provide you with hot water.

High Engineer only £150-350

Parts commonly replaced

  • Diverter valve
  • Flow turbine
  • PCB
1009 B

Your boiler's internal pump is not communicating correctly with the main control board, meaning the system cannot circulate hot water around your home.

High Engineer only £220-450

Parts commonly replaced

  • Circulating Pump
  • Puls Width Modulation (PWM) Cable
  • Main PCB

Related codes

1010

Your boiler's electronic control panel is currently unable to communicate with its internal components, meaning the system has safely shut down to prevent incorrect operation.

High Engineer only £150-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Communication wiring harness

Related codes

1010/0

Your boiler's internal computer has lost its connection with the main control board, preventing it from receiving any instructions to heat your home.

High Engineer only £120-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Wiring Harness
  • Display Interface Module

Related codes

1012

Your boiler's internal components are having trouble communicating with the main control board, similar to a computer losing its connection to a keyboard.

High Engineer only £120-350

Parts commonly replaced

  • Wiring harness
  • Internal BUS connection cable
  • PCB (Main Control Board)

Related codes

1013

Your boiler has detected that it is running at the absolute limit of its burning capacity and has shut down to protect itself from overheating.

High Engineer only £120-250

Parts commonly replaced

  • Gas valve
  • Flue gas sensor
  • Main printed circuit board

Related codes

1014

Your boiler is struggling to detect the flame needed to heat your water and has switched itself off for safety reasons.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Flame rectification sensor
  • Gas valve

Related codes

1018

Your boiler is simply reminding you that its annual service is now due to keep it running safely and efficiently.

Low Engineer only £90-140
Showing 111–120 of 276
1019

Your boiler has identified that the internal water pump setting is not configured correctly for your specific system model.

High Engineer only £120-250

Parts commonly replaced

  • Pump Control Module
  • Printed Circuit Board

Related codes

1021

Your boiler is having trouble 'talking' to your hot water tank or internal sensor, which means it cannot accurately tell if your water is hot enough.

Medium Engineer only £120-220

Parts commonly replaced

  • NTC temperature sensor
  • Wiring harness
1021 B

Your boiler is struggling to accurately measure the temperature of your hot water, which usually means your taps won't get as hot as they should.

Medium Engineer only £95-£160

Parts commonly replaced

  • DHW temperature sensor (NTC)
  • Wiring harness

Related codes

1023

Your boiler has been running for a very long time without a proper break, likely due to a system management setting or a sensor error, and needs a reset to clear the accumulated timer.

Low DIY-safe £80-120

What to check first

  1. Locate the reset button or dial on the boiler front panel
  2. Press and hold the reset button for 3 to 5 seconds
  3. Wait for the boiler to cycle through its startup routine
  4. If the code persists, turn the boiler off at the mains for 10 minutes before turning it back on

Parts commonly replaced

  • Printed Circuit Board
  • Temperature Sensor
1023 R

Your boiler has been running for a very long period without a break and has temporarily paused itself for safety and maintenance reasons.

Low DIY-safe £0-80

What to check first

  1. Press the Reset button on the boiler control panel
  2. Switch the boiler power off at the wall socket, wait 30 seconds, and switch it back on
  3. Check that your thermostat is not set to a temperature much higher than needed

Parts commonly replaced

  • None (Software reset usually required)
  • External Thermostat
1025

Your boiler is struggling to read the temperature of the water returning to it, so it has safely shut down to prevent overheating.

High Engineer only £150-250

Parts commonly replaced

  • Return temperature sensor
  • Wiring harness

Related codes

1025 -

Your boiler's internal thermometer that measures the temperature of the water coming back from the radiators has stopped working correctly, causing the system to stop as a precaution.

High Engineer only £90-160

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness connectors
1027

Your boiler has lost the connection to the sensor that helps keep your hot water ready for fast delivery.

Low Engineer only £120-220

Parts commonly replaced

  • DHW pre-heat sensor
  • Wiring harness
1037

Your boiler has lost the connection to the weather sensor outside your home and is now running on a default setting to ensure you still have heating and hot water.

Low Engineer only £120-200

Parts commonly replaced

  • Outdoor temperature sensor
  • Wiring loom
1037 W

Your boiler has lost connection with its outdoor temperature sensor, so it is running at a constant safe temperature to keep your home warm while it waits for a fix.

Low Engineer only £90-160

Parts commonly replaced

  • Weather compensation sensor
  • Sensor wiring

Related codes

Showing 121–130 of 276
1068

Your boiler is struggling to accurately read either the outside air temperature or the gas combustion quality, which may prevent it from heating your home efficiently.

Medium Engineer only £150-250

Parts commonly replaced

  • Outside temperature sensor
  • Lambda probe
  • Wiring harness
1068 W

Your boiler is having trouble measuring either the outside temperature or the oxygen levels in the flue, which is preventing it from running efficiently or starting up correctly.

High Engineer only £140-£320

Parts commonly replaced

  • Lambda sensor
  • Outside weather compensation sensor
  • Wiring harness

Related codes

1073

Your boiler has stopped working because it cannot correctly detect the temperature of the water inside because of a faulty internal sensor connection.

High Engineer only £120-220

Parts commonly replaced

  • Flow temperature sensor
  • Wiring harness

Related codes

1073 W

Your boiler has detected an electrical fault with the sensor that monitors water temperature, causing the system to shut down for safety.

High Engineer only £110-190

Parts commonly replaced

  • Flow temperature NTC sensor
  • Wiring harness connector

Related codes

1074

Your boiler has lost the connection to the sensor that measures how hot the water is inside it, so it has safely shut down to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness

Related codes

1074 W

Your boiler has stopped providing heating and hot water because it cannot accurately measure the temperature of the water leaving the unit.

High Engineer only £90-160

Parts commonly replaced

  • Flow Temperature Sensor (NTC thermistor)
  • Wiring harness connection

Related codes

1075

Your boiler has detected an electrical fault with the sensor that tracks the temperature of the water inside it, causing it to stop working to stay safe.

High Engineer only £150-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness

Related codes

1075 W

Your boiler has detected an electrical fault with an internal sensor that monitors the temperature of the main heating unit, causing it to stop running for safety.

High Engineer only £120-£200

Parts commonly replaced

  • Heat exchanger temperature sensor (NTC thermistor)
  • Internal wiring harness

Related codes

1076

Your boiler has lost communication with its internal temperature sensor, so it has safely shut down to prevent overheating.

High Engineer only £150-250

Parts commonly replaced

  • Temperature sensor
  • Wiring harness
  • Printed Circuit Board (PCB)
1076 W

Your boiler has stopped working because it cannot communicate with the part that monitors the temperature inside the main heating unit.

High Engineer only £120-£220

Parts commonly replaced

  • Heat exchanger temperature sensor (NTC)
  • Sensor wiring harness

Related codes

Showing 131–140 of 276
2051

Your boiler's computer has detected a serious internal processing error that is preventing it from operating safely.

High Engineer only £200-400

Parts commonly replaced

  • Main Control Board
  • Wiring Harness
2051 -

Your boiler's internal computer has encountered a software or hardware error and can no longer control the heating and hot water correctly.

High Engineer only £280-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Internal Wire Harness
2085

Your boiler has detected an internal software or communication error that is preventing it from operating correctly.

High Engineer only £150-300

Parts commonly replaced

  • Main Control Board (PCB)
  • Wiring harness
2085 V

Your boiler's internal computer has encountered a critical electronic failure and can no longer communicate with its own sensors or controls.

High Engineer only £250-£550

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness
2908

Your boiler's internal computer is experiencing a communication error, meaning it has safely shut itself down to prevent potential issues.

High Engineer only £250-450

Parts commonly replaced

  • Main control board
  • Wiring harness

Related codes

2908 V

Your boiler's internal computer has encountered a communication error or technical glitch that is preventing it from running properly.

High DIY-safe £180-450

What to check first

  1. Locate the Reset button on the boiler control panel
  2. Press and hold the Reset button for three seconds
  3. Wait for the boiler to restart and see if the fault code clears

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

2909

Your boiler's internal computer is experiencing a communication error and has shut down for safety to prevent incorrect operation.

High Engineer only £250-450

Parts commonly replaced

  • Main Control Board
  • Wiring Harness

Related codes

2909 -

Your boiler's internal computer has encountered a communication error or hardware fault and cannot operate correctly.

High DIY-safe £280-550

What to check first

  1. Press the Reset button on the front of the control panel for three seconds
  2. Switch the main electrical power supply to the boiler off for 30 seconds and then back on
  3. Contact a qualified engineer if the fault returns immediately after resetting

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Loom

Related codes

2910

Your boiler is having trouble breathing, meaning it cannot properly clear exhaust gases or draw in fresh air due to a possible blockage or a fan issue.

High Engineer only £150-350

Parts commonly replaced

  • Fan unit
  • Flue assembly
  • Air pressure switch

Related codes

2910 V

Your boiler has detected an issue with how exhaust gases are being discharged, causing it to shut down for safety.

High Engineer only £100-£280

Parts commonly replaced

  • Flue Fan
  • Air Pressure Switch
  • Flue Ducting Seals

Related codes

Showing 141–150 of 276
2911

Your boiler's internal computer has failed to automatically adjust its settings to ensure it burns gas safely and efficiently.

High Engineer only £150-250

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

2911 V

Your boiler has failed to set its internal flame settings correctly during a startup check and cannot run safely.

High DIY-safe £120-350

What to check first

  1. Press the 'Reset' button on the boiler control panel and hold for three seconds.
  2. Wait for the boiler to attempt the calibration process again.
  3. Ensure your gas supply is active by checking if other gas appliances in your home are working.

Parts commonly replaced

  • Ionisation Electrode
  • Gas Valve
  • Fan Assembly

Related codes

2912

Your boiler is struggling to start the internal fire necessary to produce heat, meaning it has safely shut itself down to prevent gas from building up.

High Engineer only £150-350

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

2912 V

Your boiler is struggling to detect a flame while trying to automatically adjust its settings, meaning it cannot stay running safely.

High Engineer only £120-280

Parts commonly replaced

  • Ionisation Electrode
  • Ignition Lead
  • Gas Valve

Related codes

2913

Your boiler is struggling to detect the flame accurately while it tries to set itself up, meaning it cannot safely start your heating or hot water.

High Engineer only £150-300

Parts commonly replaced

  • Ionisation electrode
  • Gas valve
  • Ignition lead

Related codes

2913 -

Your boiler is struggling to detect a stable flame while trying to set itself up, which means it cannot fire up safely to provide heating or hot water.

High Engineer only £120-£350

Parts commonly replaced

  • Ionisation Electrode
  • Flame Sensing Lead
  • Gas Valve
  • Burner

Related codes

2914

Your boiler's internal computer is failing to talk to the part that creates heat, meaning it cannot start up.

High Engineer only £180-350

Parts commonly replaced

  • Main Control Board
  • Wiring Harness

Related codes

2914 -

Your boiler’s internal computer and the part that controls the flame are unable to talk to each other, causing the system to stop working for safety.

High Engineer only £180-450

Parts commonly replaced

  • Wiring harness
  • Burner control module
  • Main PCB

Related codes

2915

Your boiler's air extraction fan is staying on longer than it should after finishing its work, which often points to an electronic communication error inside the unit.

Medium Engineer only £150-300

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)

Related codes

2915 V

Your boiler's fan is failing to switch off as it should, which means the system cannot complete its normal shutdown process.

High Engineer only £180-450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)

Related codes

Showing 151–160 of 276
2916

Your boiler has detected a potential issue with the gas flow control system after it has finished running, which may indicate a safety concern.

Emergency Engineer only £150-300

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

2916 V

Your boiler has detected that fuel is still flowing into the system after it was supposed to stop, causing it to shut down for safety.

Emergency Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • Burner control unit (PCB)

Related codes

2917

Your boiler is failing to light the internal flame needed to heat your home's water.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB board

Related codes

2917 V

Your boiler is struggling to detect a flame after it tries to light, causing the system to shut down for safety.

High Engineer only £120-£350

Parts commonly replaced

  • Flame sensing electrode
  • Ignition lead
  • Gas valve
  • PCB

Related codes

2918

Your boiler has detected an issue with the way it is burning gas and has shut itself down to ensure your safety.

Emergency Engineer only £150-350

Parts commonly replaced

  • Gas valve
  • Flue gas sensor
  • Printed Circuit Board (PCB)

Related codes

2918 -

Your boiler has detected an issue with how the gas is burning and has shut down as a safety precaution.

High Engineer only £120-280

Parts commonly replaced

  • Ionisation electrode
  • Ignition lead
  • Gas valve

Related codes

2920

Your boiler is failing to detect a flame, so it has safely shut itself down to prevent gas from escaping.

Emergency Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Flame rectification probe
  • Gas valve
  • Printed circuit board

Related codes

2920 V

Your boiler has detected an issue with the flame and has shut down as a safety precaution to ensure no unburnt gas is escaping.

High Engineer only £120-£280

Parts commonly replaced

  • Ionisation electrode
  • Ignition lead
  • Gas valve

Related codes

2921

Your boiler is currently stuck in a diagnostic testing mode used by engineers rather than operating in its normal heating mode.

High Engineer only £90-180

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

2921 -

Your boiler has been left in a professional testing mode, meaning it is currently running at a fixed output rather than responding to your heating controls.

Low DIY-safe £0-80

What to check first

  1. Locate the reset button on the front control panel.
  2. Press and hold the reset button for approximately 3 to 5 seconds.
  3. The display should return to the normal temperature reading and resume standard operation.

Related codes

Showing 161–170 of 276
2922

Your boiler has encountered an internal electronic error that is preventing it from operating correctly.

High Engineer only £250-450

Parts commonly replaced

  • Main Control Board
  • Wiring Harness

Related codes

2922 -

Your boiler's internal computer brain has detected a software or electronics error and has stopped working to protect itself.

High DIY-safe £280-550

What to check first

  1. Locate the reset button (represented by a flame with a line through it or the word 'Reset') on the front control panel.
  2. Press and hold the reset button for three seconds.
  3. Wait for the boiler to restart; if the code clears, monitor the boiler, but if it returns immediately, you will need a professional.

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Wiring harness

Related codes

2923

Your boiler has detected an issue with how the gas supply is being controlled, so it has safely shut itself down to prevent any risk.

Emergency Engineer only £200-350

Parts commonly replaced

  • Gas valve
  • Main PCB

Related codes

2923 V

Your boiler has detected an electrical communication problem with the internal gas valve, which is preventing it from safely managing the flow of fuel to the burner.

High Engineer only £180-350

Parts commonly replaced

  • Gas Valve
  • Wiring Harness
  • Printed Circuit Board (PCB)

Related codes

2924

Your boiler has detected that it cannot safely communicate with the part that controls the gas flow, so it has shut itself down to keep your home safe.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • Main printed circuit board
  • Wiring harness

Related codes

2924 V

Your boiler has stopped working because the internal computer can no longer talk to the part that controls the gas supply.

High Engineer only £180-£350

Parts commonly replaced

  • Gas valve
  • Wiring harness
  • Electronic Control Unit (PCB)

Related codes

2925

Your boiler is struggling to control the gas flow needed to heat your home, so it has safely shut itself down to prevent any issues.

High Engineer only £150-300

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

2925 V

Your boiler has stopped working because the internal brain and the gas valve are not communicating properly, meaning the system cannot safely control the flame.

High Engineer only £180-350

Parts commonly replaced

  • Gas Valve
  • Wiring Harness
  • Printed Circuit Board (PCB)

Related codes

2926

Your boiler has detected an issue with the fuel supply control system and has deliberately shut down to stay safe.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

2926 V

Your boiler has detected an electrical issue with the internal gas valve, which is preventing it from controlling the fuel flow correctly and causing it to shut down for safety.

High Engineer only £180-£350

Parts commonly replaced

  • Gas Valve
  • Control Box (PCB)
  • Wiring Harness

Related codes

Showing 171–180 of 276
2927

Your boiler has stopped working because the flame inside went out while it was trying to heat your water or home.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Ionisation probe
  • PCB

Related codes

2928

Your boiler's computer is experiencing a software or internal communication error, meaning it has safely shut down to prevent incorrect operation.

High Engineer only £150-300

Parts commonly replaced

  • Main printed circuit board (PCB)

Related codes

2928 -

Your boiler was running but the flame went out unexpectedly, causing the system to stop working for safety.

High DIY-safe £100-350

What to check first

  1. Check if other gas appliances, like a hob, are still working to ensure gas is reaching the property
  2. Check that your pre-payment gas meter has sufficient credit
  3. Press the Reset button on the boiler control panel

Parts commonly replaced

  • Flame sensing electrode
  • Ignition lead
  • Gas valve
  • Condensate trap (if blocked)

Related codes

2930

Your boiler's internal computer is experiencing a temporary communication error which has caused the system to stop working as a safety precaution.

High Engineer only £200-400

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Control unit

Related codes

2930 V

Your boiler's internal computer has encountered a software or communication error and has stopped working to protect itself.

High DIY-safe £180-350

What to check first

  1. Locate the 'Reset' button on the boiler control panel.
  2. Press and hold the reset button for three seconds.
  3. Wait for the boiler to restart; if the code clears, monitor it for 24 hours.

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Internal wiring harness

Related codes

2931

Your boiler's internal computer has experienced a temporary glitch or memory error, causing it to stop operating to protect the system.

High Engineer only £150-350

Parts commonly replaced

  • Main printed circuit board (PCB)

Related codes

2931 -

Your boiler's internal computer has encountered a communication error or hardware glitch and needs a professional inspection to determine if the main control board is failing.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Low voltage wiring harness

Related codes

2932

Your boiler's internal computer is experiencing a communication error, meaning it has safely shut down to prevent incorrect operation.

High Engineer only £200-450

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Control unit
2932 -

Your boiler's internal computer brain has encountered a software error and has stopped working to protect itself.

High DIY-safe £250-450

What to check first

  1. Press the 'Reset' button on the front control panel.
  2. Wait up to 30 seconds for the boiler to restart.
  3. If the fault persists, turn the boiler off at the fused spur switch for 1 minute before turning it back on.

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

2940

Your boiler is struggling because it is not receiving the correct amount of electrical power, which is likely due to a poor connection or a minor electrical fault.

Medium Engineer only £120-250

Parts commonly replaced

  • Printed Circuit Board
  • Wiring Harness
  • Power Supply Unit

Related codes

Showing 181–190 of 276
2940 V

Your boiler’s internal computer has encountered a critical communication error and cannot tell the system to heat your home or water.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

2941

Your boiler is struggling to pump enough water through the system, meaning it cannot heat your home or provide hot water effectively.

High Engineer only £150-300

Parts commonly replaced

  • Diverter valve
  • Central heating pump
  • System filter

Related codes

2941 B

Your boiler is struggling to operate because it is not sensing enough electricity or the water is not flowing through the system fast enough to keep it running safely.

High DIY-safe £120-280

What to check first

  1. Check that the boiler's main power switch is fully on and the plug is secure
  2. Ensure all radiator valves are fully open to allow water to circulate
  3. Check if your mains water pressure has dropped significantly
  4. Restart the boiler using the reset button

Parts commonly replaced

  • Circulation Pump
  • Printed Circuit Board (PCB)
  • Flow Temperature Sensor

Related codes

2942

Your boiler has stopped working because it cannot detect that the internal fan, which is essential for safely venting exhaust gases, is spinning correctly.

High Engineer only £250-450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

2942 -

Your boiler has stopped working because the internal computer can't communicate with the fan that safely clears away exhaust fumes.

High Engineer only £220-£450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

2943

Your boiler is struggling to work because the electricity supply it is receiving from your home's wall socket is weaker than it needs to be.

High Engineer only £120-250

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

2943 -

Your boiler is not receiving enough electrical power from the mains supply to operate safely and has shut down as a result.

High Engineer only £100-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External voltage stabilizer

Related codes

2945

Your boiler is rapidly cycling on and off because it cannot efficiently release the heat it is generating, which often points to a blockage or a bottleneck in your heating system.

Medium Engineer only £120-250

Parts commonly replaced

  • System filter
  • Heating pump

Related codes

2945 V

Your boiler is switching itself on and off too frequently, which has triggered a temporary lockout to prevent internal damage.

Low DIY-safe £0-120

What to check first

  1. Check that all radiator valves are fully open to allow water to circulate
  2. Turn off the power to the boiler, wait 30 seconds, and turn it back on
  3. Reset the boiler using the button on the control panel

Parts commonly replaced

  • None (Software reset)
  • External Thermostat
  • Circulation Pump

Related codes

2946

Your boiler's internal computer chip has identified that the electronic component containing its specific configuration settings is either incorrect or not properly connected.

High Engineer only £150-250

Parts commonly replaced

  • Code plug
  • PCB (Printed Circuit Board)

Related codes

Showing 191–200 of 276
2946 V

Your boiler's computer brain has detected an internal electronic chip that doesn't match the model or has become loose.

High Engineer only £120-250

Parts commonly replaced

  • Code plug (HCM)
  • Printed Circuit Board (PCB)

Related codes

2947

Your boiler's computer chip is not communicating correctly with the main control board, which is preventing the system from starting up safely.

High Engineer only £150-250

Parts commonly replaced

  • Code plug
  • Printed Circuit Board (PCB)

Related codes

2947 R

Your boiler’s internal computer chip is giving an incorrect signal, which means the system doesn't know which specific model it is supposed to be.

High Engineer only £120-250

Parts commonly replaced

  • HCM Code Plug
  • PCB (Printed Circuit Board)

Related codes

2948

Your boiler has attempted to ignite but failed to keep its flame burning at the required low intensity, so it has shut down as a safety precaution.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

2948 B

Your boiler is struggling to stay lit when running at a low power level, which is preventing it from providing steady heating or hot water.

High Engineer only £120-280

Parts commonly replaced

  • Ionisation electrode
  • Gas valve
  • Burner gasket

Related codes

2949

Your boiler is trying to start but the flame is failing to establish, so it has safely shut itself down to prevent gas from building up.

High Engineer only £150-350

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Condensate trap

Related codes

2949 B

Your boiler is struggling to detect a flame when it tries to work at full power, meaning it cannot provide consistent heating or hot water.

High Engineer only £120-350

Parts commonly replaced

  • Ionisation Electrode
  • Ignition Lead
  • Gas Valve
  • Printed Circuit Board (PCB)

Related codes

2950

Your boiler has failed to light the flame, which means it cannot produce any heating or hot water for your home.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

2951

Your boiler is trying to stay lit but keeps failing, which means it has automatically shut down to keep your home safe.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Condensate trap

Related codes

2951 V

Your boiler is trying to start up but cannot successfully light the gas to create a flame.

High DIY-safe £100-£250

What to check first

  1. Check that your gas emergency control valve is in the 'on' position
  2. If you have a prepaid gas meter, ensure it has sufficient credit
  3. Check if other gas appliances, like a cooker, are working to confirm gas supply
  4. Press the 'Reset' button on the boiler display panel

Parts commonly replaced

  • Ignition Electrode
  • Flame Sensing Probe
  • Gas Valve
Showing 201–210 of 276
2952

Your boiler is having trouble confirming that the gas flame is lit properly and has stopped working as a safety precaution.

High Engineer only £150-300

Parts commonly replaced

  • Ignition lead
  • Ionisation electrode
  • Printed Circuit Board (PCB)

Related codes

2952 V

Your boiler is struggling to keep its flame lit and has shut down as a safety precaution after several failed attempts to stay running.

High DIY-safe £100-280

What to check first

  1. Check if other gas appliances (like a hob) are working to confirm gas supply
  2. Ensure your decorative chimney or external flue is not blocked by debris
  3. Press the Reset button on the boiler controls to attempt a restart

Parts commonly replaced

  • Ionisation Electrode
  • Gas Valve
  • Ignition Lead

Related codes

2953

Your boiler has attempted to start but failed to detect a flame, meaning it cannot produce heat or hot water.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Control board

Related codes

2953 B

Your boiler has detected an internal error while checking for a flame, meaning it cannot safely confirm if it is burning gas correctly.

High Engineer only £150-350

Parts commonly replaced

  • Ionisation Electrode
  • Ignition Lead
  • Printed Circuit Board (PCB)

Related codes

2954

Your boiler has attempted to ignite several times but is failing to stay lit, meaning you currently have no heating or hot water.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

2954 B

Your boiler is struggling to keep its flame lit when running at its lowest power setting, which usually means it needs a professional service or clean.

High Engineer only £100-£250

Parts commonly replaced

  • Ionisation Electrode
  • Flame Sensing Probe
  • Burner gasket

Related codes

2955

Your boiler has detected that its internal settings do not match the way your heating system is physically set up, meaning it cannot safely start until these are corrected.

High Engineer only £100-250

Parts commonly replaced

  • None - requires software configuration

Related codes

2955 B

Your boiler is struggling to keep a flame going even though it is trying to run at full power, meaning it cannot provide heating or hot water until the issue is resolved.

High Engineer only £120-£350

Parts commonly replaced

  • Ionisation electrode
  • Gas valve
  • Flame sensing lead
  • PCB

Related codes

2956

Your boiler has detected a configuration setting that does not match the way your heating system is physically connected, preventing it from starting up correctly.

High Engineer only £120-250

Parts commonly replaced

  • Main printed circuit board (PCB)
  • System control sensor

Related codes

2956 O

Your boiler has been programmed with settings that do not match its internal hardware, causing it to stop working for safety.

High Engineer only £80-180

Parts commonly replaced

  • Main PCB (Control Board)
  • External Sensor

Related codes

Showing 211–220 of 276
2957

Your boiler's internal computer is experiencing a software glitch or communication error that is preventing the burner from igniting safely.

High Engineer only £180-350

Parts commonly replaced

  • Printed circuit board (PCB)
  • Wiring harness

Related codes

2957 V

Your boiler's computer has detected a change in how the internal water system is set up, which usually happens during a service or after a part has been replaced.

High Engineer only £80-150

Parts commonly replaced

  • Main PCB (Control Board)

Related codes

2958

Your boiler's main control computer is experiencing a temporary brain freeze and cannot communicate properly with the rest of the unit.

High Engineer only £200-450

Parts commonly replaced

  • Main control board
  • Wiring harness

Related codes

2958 V

Your boiler's computer has detected an internal communication failure and has locked down the system for safety.

High Engineer only £280-£550

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

2959

Your boiler's main control computer is experiencing a software or internal communication error, meaning the system has safely shut itself down to prevent further issues.

High Engineer only £250-450

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Control unit

Related codes

2959 B

Your boiler's internal computer has encountered a critical error and can no longer control the heating system safely.

High Engineer only £250-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Internal Wire Harness

Related codes

2960

Your boiler's main computer is having an internal communication error and cannot operate safely.

High Engineer only £250-400

Parts commonly replaced

  • Main Control Unit (PCB)
  • Wiring harness

Related codes

2960 B

Your boiler's internal computer has encountered a software or electronic communication error that is preventing it from running safely.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

2961

Your boiler has detected that the internal fan responsible for safely venting exhaust gases is not responding, so it has shut down to prevent unsafe operation.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

2961 V

Your boiler's internal computer has encountered an electronic error and cannot communicate properly with its own components.

High DIY-safe £250-550

What to check first

  1. Turn the boiler electrical supply off at the fused spur switch
  2. Wait 60 seconds
  3. Turn the power back on and press the Reset button

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Wiring harness

Related codes

Showing 221–230 of 276
2962

Your boiler has stopped working because it cannot move the air and exhaust gases through the system properly.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

2962 V

Your boiler has stopped working because the internal computer cannot communicate with the fan that clears exhaust gases.

High Engineer only £180-450

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • Main PCB

Related codes

2963

Your boiler has detected an incorrect temperature reading, which has caused it to shut down for safety reasons to prevent overheating.

High Engineer only £150-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness
  • Printed Circuit Board (PCB)

Related codes

2963 B

Your boiler has stopped working because the internal fan, which safely exhausts fumes, isn't spinning or starting up correctly.

High Engineer only £220-450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness
2964

Your boiler has detected that water is not flowing through it fast enough to keep it cool, so it has stopped working as a safety precaution.

High Engineer only £150-350

Parts commonly replaced

  • Central Heating Pump
  • Plate Heat Exchanger
  • Diverter Valve

Related codes

2965

Your boiler has detected that the water inside the unit is getting too hot and has automatically shut down to prevent damage.

High Engineer only £150-300

Parts commonly replaced

  • NTC temperature sensor
  • Pump
  • Heat exchanger

Related codes

2965 B

Your boiler has shut down because the water circulating inside it is getting much hotter than it should perfectly safely be.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves are fully open to allow water to flow
  2. Ensure the system pressure gauge is between 1 and 1.5 bar
  3. Try resetting the boiler using the reset button on the control panel

Parts commonly replaced

  • Circulation pump
  • Flow temperature sensor (NTC thermistor)
  • Main heat exchanger (flushing/cleaning)

Related codes

2966

Your boiler has detected that the water inside it is heating up much faster than it safely should, causing the system to shut down to prevent damage.

High Engineer only £150-350

Parts commonly replaced

  • Primary heat exchanger
  • Flow sensor
  • System filter
  • Pump

Related codes

2966 B

Your boiler is heating up too quickly because the water inside cannot flow away fast enough to cool the system down.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Check that the boiler pressure gauge is between 1.0 and 1.5 bar
  3. Ensure there are no blockages in the magnetic system filter if one is fitted
  4. Reset the boiler after checking the above

Parts commonly replaced

  • Central heating pump
  • Main heat exchanger (flushing/cleaning)
  • Flow/Return thermistors

Related codes

2967

Your boiler has detected that the water is not heating up evenly, which means it will stop working to protect itself from internal damage.

High Engineer only £150-250

Parts commonly replaced

  • NTC temperature sensor
  • Central heating pump
  • Primary heat exchanger

Related codes

Showing 231–240 of 276
2967 B

Your boiler has detected that the water is heating up too quickly or unevenly, causing it to shut down to prevent overheating.

High DIY-safe £120-350

What to check first

  1. Check that all radiator valves are fully open
  2. Check the boiler pressure gauge and top up to 1.5 bar if low
  3. Bleed your radiators to remove trapped air
  4. Reset the boiler using the reset button

Parts commonly replaced

  • Circulation Pump
  • Temperature Sensor (NTC Thermistor)
  • Main Heat Exchanger (Descaling/Flushing)

Related codes

2971

Your boiler has stopped working because the water pressure inside your heating system has dropped below the required level.

High DIY-safe £0-80

What to check first

  1. Locate the filling loop (a silver flexi-hose) or the internal key under the boiler
  2. Slowly open the valves to allow water from the mains into the system
  3. Watch the pressure gauge on the front of the boiler until it reaches the green zone (usually 1.5 bar)
  4. Close the valves firmly to stop the flow

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Expansion vessel
2972

Your boiler has detected that the electricity supply coming from your mains is weaker than required to operate safely.

High Engineer only £100-250

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

2973

Your boiler's internal computer is experiencing a communication error, meaning the system cannot safely operate your heating or hot water.

High Engineer only £250-450

Parts commonly replaced

  • Main Control Board
  • Wiring Harness

Related codes

2974

Your boiler has detected an internal software or processing error that is preventing it from operating correctly.

High Engineer only £200-400

Parts commonly replaced

  • Main control board
  • PCB

Related codes

2980

Your boiler has locked itself as a safety precaution, which means it has stopped providing heating or hot water until it is manually reset.

High DIY-safe £0-120

What to check first

  1. Locate the up and down arrow keys on the boiler display panel
  2. Press and hold both the up and down arrows simultaneously for 3 seconds
  3. Wait for the boiler to restart and monitor if the fault returns

Parts commonly replaced

  • None (Software reset)
  • Printed Circuit Board (PCB)

Related codes

2981

Your boiler has detected a critical internal error and has shut itself down as a safety precaution, meaning you currently have no heating or hot water.

High Engineer only £150-350

Parts commonly replaced

  • Control unit
  • PCB
  • Wiring harness

Related codes

3071

Your boiler is having trouble communicating with its wireless thermostat, which is preventing it from knowing when to turn the heating on.

High Engineer only £120-250

Parts commonly replaced

  • Comfort + II RF unit
  • Wiring harness
  • PCB communication module
A7

Your boiler is currently unable to accurately measure the temperature of the water it is heating, so it has stopped providing hot water to keep your system safe.

High Engineer only £120-220

Parts commonly replaced

  • Domestic Hot Water NTC Sensor

Related codes

A8

Your boiler's internal control system has lost its digital connection, meaning it cannot properly send or receive instructions to run your heating or hot water.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Communication wiring harness

Related codes

Showing 241–250 of 276
AC

Your boiler's main brain is unable to communicate with its internal control unit, which means the system has stopped working to protect itself.

High Engineer only £150-350

Parts commonly replaced

  • Control module
  • Wiring harness
  • Main PCB

Related codes

b1

Your boiler's computer is struggling to read its internal configuration settings, which is preventing it from starting up correctly.

High Engineer only £150-250

Parts commonly replaced

  • Code plug
  • PCB (Printed Circuit Board)
Boiling

Your boiler is overheating because it cannot move the hot water away from the heating unit quickly enough, or it is struggling to accurately read its own temperature.

High Engineer only £150-300

Parts commonly replaced

  • NTC Temperature Sensor
  • Central Heating Pump
  • Primary Heat Exchanger

Related codes

BURNER FAILS TO START

Your boiler is failing to ignite because it is not receiving the signal or power required to safely turn on.

High Engineer only £150-350

Parts commonly replaced

  • Control board (PCB)
  • Ignition electrode
  • Gas valve
  • Wiring harness

Related codes

Burner motor fails to operate

Your boiler's fan unit, which clears out exhaust gases, has failed to start, so the system has safely shut down to prevent unsafe operation.

High Engineer only £200-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

C1

Your boiler's internal air blower is struggling to run at the correct speed, which is preventing the system from safely igniting your heating and hot water.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)

Related codes

C4

Your boiler is struggling to shut down its internal ventilation system properly, which means it cannot safely restart or regulate itself.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)

Related codes

C6

Your boiler has detected that the internal ventilation fan is spinning faster than it should, which has caused it to shut down for safety reasons.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)

Related codes

d1

Your boiler is struggling to accurately measure the temperature of the water returning to it, which causes it to stop working to protect the system from overheating.

High Engineer only £150-250

Parts commonly replaced

  • Return NTC sensor
  • Wiring harness

Related codes

d3

Your boiler is failing to detect a request for heat from your thermostat or internal timer, likely due to a loose wire or a disconnected control link.

High Engineer only £100-200

Parts commonly replaced

  • External heating controller
  • Wiring harness
  • PCB link

Related codes

Showing 251–260 of 276
E2

Your boiler has lost its ability to accurately measure the water temperature, so it has safely shut itself down to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness

Related codes

E9

Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage or danger.

High Engineer only £150-300

Parts commonly replaced

  • NTC temperature sensor
  • Primary heat exchanger
  • Pump
  • Safety thermal cut-out

Related codes

EA

Your boiler has failed to light the flame, which means it has stopped working to keep you safe.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Condensate trap

Related codes

F0

Your boiler's computer system has encountered a general internal communication issue that is preventing it from operating correctly.

High Engineer only £150-300

Parts commonly replaced

  • Main control board
  • Wiring harness

Related codes

F7

Your boiler has detected a flame signal when it shouldn't be running, which is a safety concern that requires immediate professional attention.

Emergency Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Flame detection electrode
  • Gas valve

Related codes

FA

Your boiler has detected that a flame is still burning inside, even though it has sent a signal to turn the gas off, which indicates a serious safety monitoring fault.

Emergency Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)
  • Flame rectification electrode

Related codes

Fd

Your boiler's reset button has been held down for too long, causing the system to enter a settings mode that prevents it from firing.

Low DIY-safe

What to check first

  1. Switch the boiler off at the fused spur or mains power supply
  2. Wait for 60 seconds to ensure the electronic memory clears
  3. Switch the power back on and allow the boiler to perform a normal restart cycle

Related codes

Flame detection fault

Your boiler is failing to light the flame or keep it running, which means it cannot provide you with heating or hot water until the ignition system is serviced.

High Engineer only £120-250

Parts commonly replaced

  • Flame rectification probe
  • Ignition electrode
  • Control board

Related codes

HIGH SMOKE NUMBER

Your boiler is not burning fuel correctly, which is causing soot buildup and potential safety issues with the exhaust gases.

Emergency Engineer only £150-300

Parts commonly replaced

  • Burner nozzle
  • Flue seals
  • Gas valve

Related codes

Showing 261–270 of 276
Ignition failure

Your boiler is failing to light because the internal component responsible for sparking the flame is not positioned correctly.

High Engineer only £120-200

Parts commonly replaced

  • Ignition electrode
  • Ignition lead
  • Ignition transformer

Related codes

Incorrect CO2

Your boiler is not mixing air and fuel correctly for combustion, which could lead to unsafe operation if left unresolved.

Emergency Engineer only £120-250

Parts commonly replaced

  • Gas valve
  • Flue seal
  • Burner seal
  • Fan

Related codes

Intermittent lockout

Your boiler is struggling to stay lit reliably, causing it to shut down periodically for safety reasons.

High Engineer only £150-350

Parts commonly replaced

  • Ignition electrode
  • Flame sensing probe
  • Wiring harness
  • PCB

Related codes

LOCKOUT

Your boiler has stopped working because it cannot safely ignite or maintain its internal flame.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Flame rectification probe
  • Gas valve
  • PCB

Related codes

No LED

Your boiler has completely lost power and is not responding, meaning it cannot provide any heating or hot water until the electrical supply is restored.

High Engineer only £120-350

Parts commonly replaced

  • Printed circuit board (PCB)
  • Fuse
  • Wiring harness
No oil from nozzle

Your boiler is failing to light because the fuel supply is interrupted, blocked, or not reaching the burner as it should.

High Engineer only £120-250

Parts commonly replaced

  • Oil nozzle
  • Oil pump
  • Flexible oil hose

Related codes

Noisy operation

Your boiler is making unusual rattling or grinding noises, which usually suggests there is trapped air in the system or a internal mechanical part is starting to wear out.

Medium Engineer only £180-350

Parts commonly replaced

  • Central heating pump
  • Fan assembly
  • Pump head

Related codes

OIL SMELLS

Your boiler is leaking fuel or failing to burn it correctly, which is releasing hazardous fumes into your home.

Emergency Engineer only £150-400

Parts commonly replaced

  • Flexible oil hoses
  • Burner nozzle
  • Oil pump seals
  • Flue seals

Related codes

P1

Your boiler is currently unable to start up because a small protective electrical fuse inside the unit has blown, cutting power to internal systems.

High Engineer only £120-200

Parts commonly replaced

  • 24V internal fuse
  • PCB

Related codes

Showing 271–276 of 276
P1, P2, P3, P4

Your boiler has detected a general internal technical fault that prevents it from operating correctly.

High Engineer only £150-300

Parts commonly replaced

  • Main printed circuit board (PCB)

Related codes

P2

Your boiler is currently unable to start because an internal protective fuse has blown and will need to be replaced by a professional.

High Engineer only £120-220

Parts commonly replaced

  • 24V control fuse
  • PCB

Related codes

P3

Your boiler is struggling to power its internal control systems due to a blown electrical fuse, meaning it cannot start up correctly.

High Engineer only £120-200

Parts commonly replaced

  • Internal 24V fuse
  • Printed Circuit Board (PCB)

Related codes

Pulsation on start

Your boiler is struggling to breathe properly during startup, which prevents it from igniting smoothly and safely.

Emergency Engineer only £150-300

Parts commonly replaced

  • Flue seals
  • Gas valve
  • Burner assembly

Related codes

Red - continuous

Your boiler has stopped circulating water, meaning it cannot provide heating or hot water, and the system is currently unable to operate.

High Engineer only £250-450

Parts commonly replaced

  • Circulation Pump
  • Printed Circuit Board (PCB)

Related codes

Short Cycling

Your boiler is rapidly turning itself on and off because it cannot efficiently heat the water circulating through your radiators.

Medium Engineer only £150-300

Parts commonly replaced

  • System filter
  • Circulation pump
  • Thermostatic radiator valves

Related codes