Worcester Bosch Greenstar 8000+ GR8701iW 35 S Fault codes & diagnostics

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

Combi Natural GasLPG 2024-present
GC Numbers 41-800-2841-800-35
Download the Worcester Bosch Greenstar 8000+ GR8701iW 35 S manualThe official installation and service manual (PDF), the document these fault codes were read from. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
2 Emergency 75 High 4 Medium 22 Low
Fault codes

All 103 documented codes

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200

Your boiler is not currently experiencing a fault; it is simply indicating that it is actively running to provide central heating for your home.

Low DIY-safe

What to check first

  1. Check your thermostat to ensure the target temperature is set correctly.
  2. Wait for the house to reach temperature; the code will change once the heating demand is met.
  3. No action is required as this is an operational status code, not an error.

Related codes

Full explanation for 200
201

Your boiler is simply letting you know that it is currently busy heating up water for your taps or shower.

Low DIY-safe

What to check first

  1. No action is required as this is an operational status message rather than a breakdown.
  2. Check that your hot water taps are fully turned off.
  3. Wait for the boiler to finish its current cycle, after which the code should disappear.

Related codes

Full explanation for 201
202

Your boiler is temporarily resting to prevent it from turning on and off too frequently, which helps protect the internal components from unnecessary wear.

Low DIY-safe

What to check first

  1. Check that your room thermostat is set higher than the current room temperature
  2. Ensure all radiator valves (TRVs) are turned open to allow heat to circulate
  3. Wait up to 15 minutes for the anti-cycle timer to expire and the boiler to restart automatically

Related codes

Full explanation for 202
203

Your boiler is working correctly and is simply waiting for a signal from your thermostat or timer to start heating.

Low DIY-safe

What to check first

  1. Check that your room thermostat is turned up higher than the current room temperature.
  2. Ensure your heating programmer or app is set to an 'On' period.
  3. Check if your wireless thermostat has run out of batteries.

Related codes

Full explanation for 203
204

Your boiler has sensed that the water temperature has risen above the level it was set to reach, leading it to shut down for safety.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open to allow water to circulate.
  2. Ensure there is enough water pressure in the system by checking the digital gauge.
  3. Restart the boiler using the reset button on the touch screen.

Parts commonly replaced

  • Circulation Pump
  • Flow Temperature Sensor (NTC)
  • Main Heat Exchanger (Cleaning)

Related codes

Full explanation for 204
208

Your boiler is currently set to a manual testing mode used by engineers to check emissions, which prevents it from operating normally.

Low DIY-safe

What to check first

  1. Locate the 'Chimney Sweep' button (icon looks like a brush) on the touch screen display.
  2. Press and hold the button for approximately 3 to 5 seconds.
  3. The display should return to the standard temperature screen once the mode is deactivated.

Related codes

Full explanation for 208
214

Your boiler has detected that the internal fan is not spinning as expected during start-up, so it has safely shut down to prevent unsafe operation.

High Engineer only £180-350

Parts commonly replaced

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

Related codes

Full explanation for 214
224

Your boiler has shut down because a safety sensor has detected that it is getting far too hot, likely due to a blockage or a pump failure.

High Engineer only £120-£350

Parts commonly replaced

  • Overheat Thermostat
  • Circulating Pump
  • Heat Exchanger

Related codes

Full explanation for 224
227

Your boiler is failing to light the gas even though it is trying to, which prevents your heating and hot water from working.

High DIY-safe £120-350

What to check first

  1. Check if other gas appliances (like a hob) are working to ensure gas is reaching the property
  2. Check if your gas meter has credit (if using a pre-payment meter)
  3. Hold the 'Reset' button on the front of the boiler for 3 seconds

Parts commonly replaced

  • Ignition Electrode
  • Flame Sensing Probe
  • Gas Valve
  • Ignition Lead

Related codes

Full explanation for 227
228

Your boiler thinks a flame is burning even though it hasn't actually sparked or started, causing it to shut down for safety.

High Engineer only £120-£280

Parts commonly replaced

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

Related codes

Full explanation for 228
Showing 11–20 of 103
229

Your boiler's flame has gone out while it was trying to heat your water, which means the boiler has safely shut itself down to prevent any issues.

High Engineer only £120-250

Parts commonly replaced

  • Electrodes
  • Gas valve
  • Gas pressure regulator
  • Printed circuit board

Related codes

Full explanation for 229
232

Your boiler has been intentionally switched off or put into standby mode by an external device, such as a smart thermostat, a programmer, or a safety control system.

High Engineer only £90-180

Parts commonly replaced

  • External wiring
  • Heating programmer
  • Smart thermostat receiver

Related codes

Full explanation for 232
233

Your boiler's computer is having trouble recognising its own internal settings, which is preventing it from starting up correctly.

High Engineer only £250-450

Parts commonly replaced

  • Main control board
  • Coding plug

Related codes

Full explanation for 233
234

Your boiler is not detecting the electrical connection to the gas supply mechanism, meaning it cannot safely ignite to provide heating or hot water.

High Engineer only £150-250

Parts commonly replaced

  • Gas valve
  • Wiring harness
  • PCB

Related codes

Full explanation for 234
235

Your boiler's internal computer is confused because its software settings don't match the specific model hardware installed.

High Engineer only £150-300

Parts commonly replaced

  • PCB
  • Programming Key

Related codes

Full explanation for 235
237

Your boiler has detected a general internal communication failure, meaning it cannot safely operate its main control systems.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

Full explanation for 237
238

Your boiler's main control unit has identified an internal electronic error and has shut down to prevent potential damage.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Wiring harness

Related codes

Full explanation for 238
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

Full explanation for 242
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

Full explanation for 244
245

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

High Engineer only £200-400

Parts commonly replaced

  • Main Control Board
  • Wiring harness
Full explanation for 245
Showing 21–30 of 103
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

Full explanation for 246
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

Full explanation for 247
248

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

High Engineer only £250-450

Parts commonly replaced

  • Main control unit (PCB)
  • Wiring harness
  • Display interface

Related codes

Full explanation for 248
249

Your boiler's internal computer is experiencing a temporary communication error, causing it to stop operating as a protective measure.

High Engineer only £250-450

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Wiring harness
Full explanation for 249
250

Your boiler's internal computer has encountered a critical communication error, meaning it has safely shut itself down to prevent potential damage.

High Engineer only £250-450

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Control unit

Related codes

Full explanation for 250
251

Your boiler’s internal computer is experiencing a software glitch or a communication error that is preventing it from running safely.

High Engineer only £150-350

Parts commonly replaced

  • Main control board
  • Wiring harness

Related codes

Full explanation for 251
252

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

  • Printed Circuit Board (PCB)
  • Control wiring harness

Related codes

Full explanation for 252
253

Your boiler's computer has encountered an internal error and cannot operate, which means you currently have no heating or hot water.

High Engineer only £250-450

Parts commonly replaced

  • Main Control Unit
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 253
254

Your boiler has detected an internal electrical problem with its main computing brain, preventing it from operating safely.

High Engineer only £250-450

Parts commonly replaced

  • Main Control Unit (PCB)
  • Wiring harness

Related codes

Full explanation for 254
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

Full explanation for 257
Showing 31–40 of 103
258

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

High Engineer only £200-450

Parts commonly replaced

  • Main Control Board
  • Wiring Harness
Full explanation for 258
259

Your boiler's internal computer is experiencing a software or communication error and needs to be restarted or investigated by a professional.

High Engineer only £150-350

Parts commonly replaced

  • Main printed circuit board
  • Wiring harness
Full explanation for 259
262

Your boiler has detected an internal computer error that is preventing it from starting up correctly.

High Engineer only £200-400

Parts commonly replaced

  • Main control board
  • Wiring harness

Related codes

Full explanation for 262
263

Your boiler's internal computer has encountered a memory or communication error, which prevents it from operating safely.

High Engineer only £250-450

Parts commonly replaced

  • Main Control Board (PCB)
  • Wiring Harness

Related codes

Full explanation for 263
265

Your boiler is temporarily turning itself off because your radiators or taps aren't taking away the heat as fast as the boiler is producing it, often due to poor water flow.

Medium Engineer only £120-250

Parts commonly replaced

  • Central heating pump
  • System filter
  • Diverter valve

Related codes

Full explanation for 265
268

Your boiler has detected an internal communication glitch during its self-test phase, which prevents it from firing up safely.

High Engineer only £150-300

Parts commonly replaced

  • Main control board (PCB)
  • Wiring harness

Related codes

Full explanation for 268
269

Your boiler has detected that the flame is not burning as it should and has shut itself down to keep your home safe.

High Engineer only £150-300

Parts commonly replaced

  • Ionisation electrode
  • Ignition lead
  • Gas valve
  • Printed circuit board

Related codes

Full explanation for 269
273

Your boiler has detected that the flame-making process has stopped, preventing your heating or hot water from working.

High Engineer only £150-300

Parts commonly replaced

  • Fan
  • Air pressure switch
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 273
281

Your boiler is struggling because the internal water pump is either jammed or air is trapped inside the system, preventing water from circulating properly.

High Engineer only £150-300

Parts commonly replaced

  • Circulation pump
  • Automatic air vent

Related codes

Full explanation for 281
283

Your boiler is currently going through its normal ignition sequence to fire up and provide heat or hot water.

Low Engineer only

Related codes

Full explanation for 283
Showing 41–50 of 103
284

Your boiler is having trouble managing the balance of air and gas required for safe combustion and has locked itself out to prevent potential issues.

High Engineer only £150-300

Parts commonly replaced

  • Gas valve
  • Gas valve harness

Related codes

Full explanation for 284
305

Your boiler is temporarily pausing the hot water production to prevent itself from overheating or cycling on and off too frequently.

Low DIY-safe

What to check first

  1. Wait up to 15 minutes for the anti-cycle timer to expire
  2. Ensure hot water taps are fully closed
  3. Check that the hot water temperature setting on the control panel is not set excessively high

Related codes

Full explanation for 305
306

Your boiler is still detecting a flame even though it has tried to shut off the gas supply, which is a safety conflict.

Emergency Engineer only £180-450

Parts commonly replaced

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

Related codes

Full explanation for 306
357

Your boiler is currently running a brief automatic test to clear any lingering gases from the internal system before it attempts to fire up again.

Low Engineer only

Parts commonly replaced

  • Flue fan
  • Air pressure switch
  • Venturi
Full explanation for 357
360

Your boiler has detected an internal communication error with its control chip, meaning it cannot start safely.

High Engineer only £150-300

Parts commonly replaced

  • Code plug
  • Main printed circuit board (PCB)

Related codes

Full explanation for 360
362

Your boiler has stopped working because its internal memory chip is either missing, damaged, or incorrect.

High Engineer only £100-250

Parts commonly replaced

  • Code plug
  • Printed circuit board (PCB)

Related codes

Full explanation for 362
363

Your boiler's electronic control system has detected an internal communication or sensing error, meaning it has safely shut down to prevent unsafe operation.

High Engineer only £150-350

Parts commonly replaced

  • Ionisation cable
  • Ignition electrode
  • Control unit / PCB

Related codes

Full explanation for 363
604

Your boiler has detected an internal electronic brain error and has safely shut down to prevent damage.

High Engineer only £250-450

Parts commonly replaced

  • Burner Controller (PCB)
Full explanation for 604
811

Your boiler has failed its routine high-temperature anti-bacteria cycle for the hot water system, meaning the water did not reach the required sterilization temperature.

Low Engineer only £100-£250

Parts commonly replaced

  • Hot water temperature sensor
  • Water pump

Related codes

Full explanation for 811
Showing 51–60 of 103
815

Your boiler has detected an issue with a temperature sensor, which may have been accidentally turned on in the settings or affected by moisture.

Low DIY-safe £90-180

What to check first

  1. Check the boiler control menu to see if the low loss header setting was accidentally enabled.
  2. Restart your boiler to clear temporary system glitches.
  3. If the error persists, contact a heating engineer to check the sensor and wiring for moisture.

Parts commonly replaced

  • Low loss header temperature sensor
  • Wiring harness

Related codes

Full explanation for 815
1010

Your boiler has lost internal communication between its main control parts, meaning it cannot properly send or receive instructions to run your heating.

High Engineer only £150-350

Parts commonly replaced

  • PCB
  • Programming Key
Full explanation for 1010
1013

Your boiler has reached its scheduled maintenance limit and needs a service reset.

Low Engineer only £80-120
Full explanation for 1013
1017

Your boiler has stopped working because the water pressure inside the system has dropped too low.

High DIY-safe

What to check first

  1. Locate the filling loop or key beneath your boiler
  2. Open the valves gently to let water in while watching the pressure gauge
  3. Stop filling when the needle reaches between 1 and 1.5 bar, then close the valves tightly

Parts commonly replaced

  • Water pressure sensor
  • Filling loop

Related codes

Full explanation for 1017
1018

Your boiler is simply reminding you that its scheduled annual service is due based on the date set in its system.

Low DIY-safe £0-100

What to check first

  1. Check the current date and service interval settings in the boiler's menu
  2. Reset the maintenance reminder code via the reset menu once your annual service has been completed by a Gas Safe engineer
Full explanation for 1018
1019

Your boiler has temporarily stopped working because it cannot properly communicate with its internal water pump.

High Engineer only £150-350

Parts commonly replaced

  • Boiler Pump
  • Pump Communication Wiring Harness
  • Main Circuit Board

Related codes

Full explanation for 1019
1022

Your boiler is struggling to accurately read the temperature of your hot water cylinder due to a loose or faulty sensor.

Medium Engineer only £90-180

Parts commonly replaced

  • Cylinder temperature sensor
  • Sensor connecting lead

Related codes

Full explanation for 1022
1023

Your boiler has reached a set operating or maintenance time limit and needs to be serviced and reset by a professional.

Low Engineer only £80-150
Full explanation for 1023
1025

Your boiler has detected that a vital temperature sensor is missing or not properly connected, so it has safely shut down to prevent damage.

High Engineer only £120-£250

Parts commonly replaced

  • Return temperature sensor
  • Wiring harness

Related codes

Full explanation for 1025
1037

Your boiler has detected a fault with the outdoor temperature sensor, but it is safely using an internal backup to keep your heating running in the meantime.

Low Engineer only £90-180

Parts commonly replaced

  • Outside temperature sensor
  • Wiring cable

Related codes

Full explanation for 1037
Showing 61–70 of 103
1065

Your boiler's digital pressure sensor is either unplugged or malfunctioning, meaning the system cannot accurately read its internal water level.

Low Engineer only £90-180

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness

Related codes

Full explanation for 1065
1068

Your boiler has lost connection with its outdoor temperature sensor, meaning it cannot properly adjust to outside weather conditions.

Low Engineer only £90-180

Parts commonly replaced

  • Outside temperature sensor
  • Sensor wiring harness

Related codes

Full explanation for 1068
1075

Your boiler has temporarily stopped working because a temperature sensor is sending an incorrect electrical reading, which prevents the system from safely monitoring how hot it is getting.

High Engineer only £120-250

Parts commonly replaced

  • Heat Exchanger Temperature Sensor
  • Wiring Harness

Related codes

Full explanation for 1075
1076

Your boiler has temporarily stopped working because it has lost the connection to one of its internal temperature sensors.

High Engineer only £120-£250

Parts commonly replaced

  • Temperature Sensor
  • Wiring Harness
  • PCB

Related codes

Full explanation for 1076
2085

Your boiler has detected an internal computer error and needs to be safely restarted or checked by a professional.

High DIY-safe £250-500

What to check first

  1. Press the reset button on your boiler display panel.
  2. Turn the boiler off at the fused spur switch, wait for 30 seconds, and turn it back on.
  3. If the code persists, a Gas Safe registered engineer will need to inspect the internal wiring and components.

Parts commonly replaced

  • PCB
Full explanation for 2085
2908

Your boiler's main electronic brain has experienced an internal system glitch that requires a restart or professional replacement.

High DIY-safe £250-£450

What to check first

  1. Turn off the boiler using the power button on the control panel.
  2. Wait for approximately 30 seconds to allow the internal electronics to fully reset.
  3. Turn the boiler back on and check if the error code clears.

Parts commonly replaced

  • Burner controller (PCB)
Full explanation for 2908
2910

Your boiler has detected an issue with the exhaust flue system or internal water drainage, so it has safely shut down to prevent any unsafe operation.

Emergency Engineer only £100-250

Parts commonly replaced

  • Condensate trap
  • Siphon
  • Flue seal

Related codes

Full explanation for 2910
Showing 71–80 of 103
2914

Your boiler has detected an internal electrical control system glitch and has temporarily locked out for safety.

Medium DIY-safe £150-350

What to check first

  1. Turn the boiler off at the fused spur switch or wall socket.
  2. Wait for approximately 30 seconds to allow the internal electrical components to fully reset.
  3. Turn the boiler back on and check if the fault code clears or if normal operation resumes.

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Wiring harness

Related codes

Full explanation for 2914
2915

Your boiler's main internal computer has encountered a memory or communication error, preventing the system from running safely.

High Engineer only £250-550

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • HMI (Display Interface Panel)

Related codes

Full explanation for 2915
2916

Your boiler has detected an internal electrical communication error, meaning it cannot properly coordinate its functions to provide heat and hot water.

High Engineer only £250-£650

Parts commonly replaced

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

Related codes

Full explanation for 2916
2920

Your boiler has detected a problem with how it tracks its own flame, causing it to shut down for safety purposes.

High Engineer only £120-350

Parts commonly replaced

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

Related codes

Full explanation for 2920
2923

Your boiler has detected an internal electrical communication error, which means it has stopped running to prevent damage to its electronic components.

High DIY-safe £280-550

What to check first

  1. Press the 'Reset' button on the front display panel and hold for three seconds.
  2. Wait up to 10 minutes for the boiler to complete its restart sequence.
  3. Ensure your household electricity supply is stable and you have not recently had a power cut.

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

Full explanation for 2923
2924

Your boiler has detected an internal electrical problem that is preventing it from starting up safely.

High Engineer only £250-£550

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Internal Wiring Harness

Related codes

Full explanation for 2924
2925

Your boiler has experienced an internal electrical error that has caused it to stop working for safety.

High DIY-safe £250-550

What to check first

  1. Press the 'Reset' button on the front control panel once.
  2. Wait up to 10 minutes to see if the boiler restarts normally.
  3. If the code persists or returns immediately, do not attempt further repairs and contact a Gas Safe engineer.

Parts commonly replaced

  • Internal Wiring Harness
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 2925
2926

Your boiler's internal computer has detected a general electrical communication error and has shut down as a safety precaution.

High Engineer only £180-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Internal Wiring Harness

Related codes

Full explanation for 2926
2927

Your boiler's main control unit has detected an electrical communication failure, meaning the system cannot safely operate your heating or hot water.

High Engineer only £200-450

Parts commonly replaced

  • Main Control Unit (PCB)
  • Wiring harness

Related codes

Full explanation for 2927
2928

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

High Engineer only £180-350

Parts commonly replaced

  • Main Control Board (PCB)
  • Wiring harness

Related codes

Full explanation for 2928
Showing 81–90 of 103
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

Full explanation for 2931
2940

Your boiler has detected an internal communication error or hardware fault within its main control system, preventing it from firing up safely.

High Engineer only £250-550

Parts commonly replaced

  • Burner Control Unit
  • Main PCB
  • Wiring Harness

Related codes

Full explanation for 2940
2946

Your boiler's computer memory chip is not being recognised or is mismatched, which prevents the system from starting up.

High Engineer only £120-280

Parts commonly replaced

  • HCM code plug
  • PCB (Control board)

Related codes

Full explanation for 2946
2948

Your boiler is struggling to stay lit when it is running at its lowest power level, often causing it to shut down for safety.

High Engineer only £120-280

Parts commonly replaced

  • Ionisation Probe
  • Gas Valve
  • Electrode Set

Related codes

Full explanation for 2948
2949

Your boiler has attempted to ignite several times but is failing to stay lit, so it has shut down as a safety precaution.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification probe

Related codes

Full explanation for 2949
2950

Your boiler has tried to start up but cannot detect a flame, meaning it cannot provide heating or hot water.

High DIY-safe £100-£350

What to check first

  1. Check if other gas appliances (like a hob) are working to ensure gas is reaching the property
  2. Check that your prepaid gas meter has credit
  3. Try resetting the boiler using the reset button on the touchscreen

Parts commonly replaced

  • Ignition Electrode
  • Flame Sensing Probe
  • Gas Valve
  • Ignition Lead

Related codes

Full explanation for 2950
2951

Your boiler is repeatedly trying to stay lit but failing, which means it will stop working to keep you safe.

High Engineer only £150-350

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification probe

Related codes

Full explanation for 2951
2952

Your boiler has detected an internal error while trying to confirm the flame is burning correctly, causing it to shut down for safety.

High Engineer only £150-300

Parts commonly replaced

  • Printed circuit board (PCB)
  • Ionisation electrode
  • Wiring harness

Related codes

Full explanation for 2952
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

Full explanation for 2955
2956

Your boiler has detected that a specific accessory or additional part has been connected and needs to be set up through the control panel.

Low DIY-safe £0-80

What to check first

  1. Navigate to the 'Settings' menu on the boiler screen
  2. Select 'Hydraulic Configuration' and confirm the installed setup
  3. Press and hold 'Reset' to clear the message once the settings are saved

Related codes

Full explanation for 2956
Showing 91–100 of 103
2957

Your boiler's electronic control system has encountered an internal communication error and has safely shut itself down to prevent further damage.

High Engineer only £250-450

Parts commonly replaced

  • Main Control Board
  • Wiring Harness
Full explanation for 2957
2961

Your boiler is unable to detect that its internal air fan is spinning, so it has safely shut itself down to prevent operation without proper ventilation.

High Engineer only £180-350

Parts commonly replaced

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

Related codes

Full explanation for 2961
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

Full explanation for 2962
2963

Your boiler has detected that the sensors monitoring its internal temperature are giving incorrect readings or have failed, causing the system to shut down for safety.

High Engineer only £140-£240

Parts commonly replaced

  • Heat exchanger temperature sensor
  • Flow temperature sensor
  • Wiring harness

Related codes

Full explanation for 2963
2965

Your boiler has sensed that the water inside is getting much hotter than it should be and has shut down as a safety precaution.

High DIY-safe £120-280

What to check first

  1. Ensure all radiator valves (TRVs) are turned to the highest setting
  2. Check that the boiler pressure gauge is between 1 and 1.5 bar
  3. Reset the boiler using the display panel to see if the fault clears

Parts commonly replaced

  • Circulation Pump
  • Flow Temperature Sensor (NTC)
  • Main Heat Exchanger (Flushing)

Related codes

Full explanation for 2965
2966

Your boiler is overheating too quickly because water isn't moving through the system fast enough.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the system pressure is between 1.0 and 1.5 bar
  3. Bleed your radiators to remove any trapped air

Parts commonly replaced

  • Circulating pump
  • Main heat exchanger (flushing required)
  • Temperature sensors

Related codes

Full explanation for 2966
2968

Your boiler has detected that the water pressure is too low and it is currently trying to top itself up automatically.

Low DIY-safe £0-120

What to check first

  1. Wait a few minutes to see if the 'Intelligent Filling System' completes the top-up automatically.
  2. If it does not stop, check the display for a prompt to manual override the filling valve.
  3. Check visible pipework and radiators for any signs of water leaks.

Parts commonly replaced

  • None (Software notification)
  • Automatic Filling Link (if faulty)

Related codes

Full explanation for 2968
2969

Your boiler's automatic filling system has topped up the water pressure too many times in a short period, suggesting there may be a leak in your heating system.

High Engineer only £100-350

Parts commonly replaced

  • Automatic filling valve
  • Expansion vessel
  • Pressure relief valve

Related codes

Full explanation for 2969
2970

Your boiler has detected that the water pressure in your heating system is falling much faster than normal, which usually indicates a significant leak or a fault with the pressure sensor.

High DIY-safe £90-250

What to check first

  1. Check all visible radiators and pipes for signs of water leaks
  2. Top up the system pressure using the internal filling link to between 1 and 1.5 bar
  3. Monitor the pressure gauge to see if it drops rapidly again after refilling

Parts commonly replaced

  • Pressure Sensor
  • Expansion Vessel
  • PRV (Pressure Relief Valve)

Related codes

Full explanation for 2970
2971

Your boiler has detected that the water pressure in the system has dropped below the minimum level required to operate safely.

High DIY-safe £0-120

What to check first

  1. Locate the integrated filling link handle underneath the boiler (on some models) or the external braided filling loop.
  2. Slowly pull the lever or open the valves to allow water into the system while watching the digital display or pressure gauge.
  3. Close the valves firmly once the pressure reaches 1.5 bar and the fault code disappears.

Parts commonly replaced

  • Intelligent Filling Link
  • Expansion Vessel
  • Pressure Sensor

Related codes

Full explanation for 2971
Showing 101–103 of 103
2972

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

High Engineer only £120-250

Parts commonly replaced

  • External fuse spur
  • Main printed circuit board (PCB)
  • Power supply cabling

Related codes

Full explanation for 2972
2980

Your boiler has locked itself for safety due to a temporary operational issue, which can often be cleared by following the on-screen reset instructions.

Medium DIY-safe

What to check first

  1. Locate the display screen on your Worcester Bosch boiler.
  2. Press and hold both the up and down arrow keys simultaneously for 3 seconds.
  3. Check if the boiler unlocks and resumes normal operation. If the fault persists, contact a qualified engineer.
Full explanation for 2980
2981

Your boiler has experienced a safety lockout and needs you to try resetting it, or call an engineer if the lockout persists.

High DIY-safe £90-200

What to check first

  1. Locate the control panel on your boiler
  2. Press and hold both the up and down arrow keys simultaneously for 3 seconds
  3. Check if the boiler unlocks and resumes normal operation

Parts commonly replaced

  • PCB
  • Gas valve
  • Ignition lead

Related codes

Full explanation for 2981
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