Baxi Performa Fault codes & diagnostics

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

Combi Natural Gas 24-28 kW 2002-2010 Discontinued

Replaced by: Potterton Titanium

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.
2 Emergency 108 High 13 Medium 6 Low
Just want the most common Baxi Performa faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 129 documented codes

Tap any card for details

LED / flash-pattern codes
1 green flash

Your boiler has reached its set temperature and is temporarily pausing its burner; this is a normal part of how the heating cycle works.

Low DIY-safe

What to check first

  1. Check that your room thermostat is set to the desired temperature
  2. Wait a few minutes for the boiler to restart when heat is needed again
  3. Ensure radiators are turned on if you have no heat
Full explanation for 1 green flash
1 red flash

Your boiler has likely stopped heating because the water inside has become too hot or the temperature sensors are reporting an incorrect reading.

High DIY-safe £90-180

What to check first

  1. Turn off the boiler at the electrical switch
  2. Wait 10 minutes for the unit to cool down
  3. Turn the selector switch to the 'Reset' position for five seconds and then back to the desired mode

Parts commonly replaced

  • NTC Temperature Sensor
  • Overheat Thermostat
  • Circulation Pump

Related codes

Full explanation for 1 red flash
2 red flashes

Your boiler has got too hot and has shut itself down as a safety precaution.

High DIY-safe £90-280

What to check first

  1. Check that all radiator valves are open and not turned off.
  2. Ensure your system water pressure is between 1 and 1.5 bar on the gauge.
  3. Turn the selector switch to the reset position for five seconds, then back to the desired mode.

Parts commonly replaced

  • Overheat Thermostat
  • Circulating Pump
  • Central Heating Return Filter

Related codes

Full explanation for 2 red flashes
3 green flashes

Your boiler has briefly lost its flame and is trying to restart itself automatically.

Medium DIY-safe £80-250

What to check first

  1. Monitor the boiler to see if it clears the fault and restarts automatically
  2. Check that other gas appliances in the home are working correctly
  3. If the fault persists and turns to red flashes, attempt a manual reset
  4. Ensure the condensate pipe has not frozen if the weather is extremely cold

Parts commonly replaced

  • Flame sensing electrode
  • Ignition lead
  • Gas valve

Related codes

Full explanation for 3 green flashes
3 red flashes

Your boiler has tried to light the gas five times without success and has now locked itself out for safety.

High DIY-safe £100-£250

What to check first

  1. Check that your credit or prepaid gas meter has sufficient funds.
  2. Ensure other gas appliances in your home, like a hob, are working correctly.
  3. Press and hold the reset button for five seconds to see if the boiler restarts.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Spark Generator

Related codes

Full explanation for 3 red flashes
4 green flashes

Your boiler is experiencing a brief communication hiccup between its internal electronic parts and should fix itself automatically.

Low DIY-safe £0-120

What to check first

  1. Wait for the boiler to complete its self-reset process
  2. If the lights continue to flash, turn the selector switch to the 'Reset' position for five seconds
  3. Ensure the power supply to the boiler is stable and not fluctuating

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

Full explanation for 4 green flashes
5 green flashes

Your boiler's internal computer has had a temporary communication glitch and is attempting to fix itself automatically.

Low DIY-safe £0-350

What to check first

  1. Wait for the boiler to complete its automatic self-reset process
  2. Turn the selector switch to the 'Reset' position for five seconds if the flashing continues
  3. Ensure the power supply to the boiler is stable and not fluctuating

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

Full explanation for 5 green flashes
5 red flashes

Your boiler's internal memory chip or main control board has developed a communication fault and cannot remember its settings.

High Engineer only £180-£350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Parameter Storage Unit (PSU)
Full explanation for 5 red flashes
6 green flashes

Your boiler has experienced a temporary hiccup and should automatically restart itself shortly.

Low DIY-safe £0-80

What to check first

  1. Wait up to 15 minutes for the system to automatically reset
  2. Ensure your gas and electricity supplies are stable
  3. Turn the selector switch to the reset position and back if the lights persist

Parts commonly replaced

  • No parts usually required
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 6 green flashes
Showing 11–20 of 129
6 red flashes

Your boiler has detected a general internal glitch or a sensor problem that is preventing it from running properly.

High Engineer only £100-280

Parts commonly replaced

  • Flow Temperature Sensor
  • Central Heating NTC Sensor
  • Main Control Board

Related codes

Full explanation for 6 red flashes
FLASH FLASH ON

Your boiler has stopped working because the fan that helps remove exhaust gases is not spinning or communicating correctly with the system.

High Engineer only £180-£350

Parts commonly replaced

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

Related codes

Full explanation for FLASH FLASH ON
FLASH OFF FLASH

Your boiler has detected that the incoming electrical power is too low to operate safely, which is usually caused by a problem with the mains supply or a faulty internal circuit board.

High Engineer only £180-£350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Transformer
Full explanation for FLASH OFF FLASH
FLASH OFF ON

Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.

High DIY-safe £90-280

What to check first

  1. Check that all radiator valves are fully open to allow water to flow.
  2. Wait 30 minutes for the boiler to cool down completely.
  3. Baxi Performa models often reset by turning the selector switch to 'R' for five seconds and then back to the original position.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Heat Exchanger (De-scaling)
Full explanation for FLASH OFF ON
FLASH ON FLASH

Your boiler's internal computer has encountered a critical error and cannot tell the system how to operate safely.

High Engineer only £250-£450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

Full explanation for FLASH ON FLASH
FLASH ON ON

Your boiler's internal computer brain has developed a critical error and can no longer control the heating or hot water safely.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board
  • Wiring Harness

Related codes

Full explanation for FLASH ON ON
ON FLASH FLASH

Your boiler is struggling to move water around the system or has detected it is getting too hot too quickly without enough water inside.

High DIY-safe £150-350

What to check first

  1. Check the pressure gauge is between 1.0 and 1.5 bar
  2. Use the filling loop to top up the pressure if it is too low
  3. Ensure all radiator valves and isolation valves are fully open

Parts commonly replaced

  • Circulating pump
  • Primary heat exchanger
  • Overheat thermostat

Related codes

Full explanation for ON FLASH FLASH
ON OFF FLASH

Your boiler has detected an electrical wiring issue where the power supply wires are connected in the wrong order.

High Engineer only £80-150

Parts commonly replaced

  • External wiring
  • Main PCB
Full explanation for ON OFF FLASH
ON ON FLASH

Your boiler's internal computer has developed a fault and is unable to control the system safely.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Internal Wiring Harness
Full explanation for ON ON FLASH
Digital codes
110

Your boiler has become too hot and has shut itself down for safety, which is often caused by trapped air blocking the flow of water.

High DIY-safe £90-250

What to check first

  1. Turn off the boiler and wait for it to cool down completely.
  2. Use a radiator key to bleed all radiators to remove any trapped air.
  3. Check the boiler pressure gauge and top up to between 1 and 1.5 bar if it has dropped.
  4. Perform a 'Reset' by turning the selector switch to the R position for at least five seconds.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Temperature Sensor (NTC)

Related codes

Full explanation for 110
117

Your boiler has too much water inside its system, which is causing it to shut down for safety.

High DIY-safe £0-120

What to check first

  1. Check that the filling loop valves are tightly closed
  2. Bleed water from a radiator using a bleed key to reduce the pressure
  3. Monitor the pressure gauge until it returns to between 1 and 1.5 bar
  4. Restart the boiler once the pressure is at the correct level

Parts commonly replaced

  • Filling loop valve
  • Pressure relief valve (PRV)
  • Expansion vessel

Related codes

Full explanation for 117
118

Your boiler has stopped working because the water pressure inside the system is too low for it to operate safely.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath the boiler.
  2. Open the small taps on the filling loop to allow water into the system.
  3. Watch the pressure gauge until it reaches between 1 and 1.5 bar, then close the taps tightly.

Parts commonly replaced

  • Filling loop
  • Pressure sensor
  • Expansion vessel

Related codes

Full explanation for 118
119

Your boiler has stopped working because the water pressure in the central heating system has dropped too low and needs to be topped up.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.
  2. Open the one or two taps on the loop slowly until you hear water flowing.
  3. Watch the pressure gauge until it reaches between 1 and 1.5 bar, then close the taps fully.

Parts commonly replaced

  • External filling loop
  • Expansion vessel
  • Pressure sensor

Related codes

Full explanation for 119
125

Your boiler has detected that water is not moving through the system properly, which is causing it to shut down to prevent overheating.

High DIY-safe £180-£350

What to check first

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

Parts commonly replaced

  • Circulation Pump
  • Primary Heat Exchanger (De-scaling)
  • Flow Temperature Sensor

Related codes

Full explanation for 125
127

Your boiler has failed to heat the water to a high enough temperature to safely kill off any potential bacteria in the system.

Medium Engineer only £90-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Diverter Valve
  • PCB
Full explanation for 127
128

Your boiler started to heat up but the flame went out unexpectedly while it was running.

High Engineer only £120-£350

Parts commonly replaced

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

Related codes

Full explanation for 128
133

Your boiler has tried to light several times but has been unable to successfully create or detect a flame.

High DIY-safe £100-£350

What to check first

  1. Check if your gas supply is active and other gas appliances are working
  2. If you have a prepaid gas meter, ensure it has sufficient credit
  3. Press and hold the reset button for at least five seconds to restart the ignition sequence

Parts commonly replaced

  • Ignition lead and electrodes
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 133
153

Your boiler has gone into a safety lockout mode because the reset button has been held down for too long or there is an internal communication error.

High DIY-safe £0-180

What to check first

  1. Locate the selector switch on the front of the boiler control panel.
  2. Turn the selector switch to the 'R' (Reset) position and hold it for at least 5 seconds.
  3. Return the switch to the central or desired operating position and wait for the boiler to restart.

Parts commonly replaced

  • None (Reset only)
  • Main PCB (if fault persists)

Related codes

Full explanation for 153
160

Your boiler has identified a problem with the fan that safely pushes waste gases out of your home, causing the system to shut down for safety.

High Engineer only £250-£450

Parts commonly replaced

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

Related codes

Full explanation for 160
Showing 31–40 of 129
162

Your boiler has detected an issue with how it clears exhaust gases, which has caused it to stop running for safety reasons.

High Engineer only £120-280

Parts commonly replaced

  • Air Pressure Switch
  • Venturi Tube
  • Fan Assembly

Related codes

Full explanation for 162
164

Your boiler has detected a problem with the internal sensor or switch that monitors water movement, which prevents it from firing up for heating or hot water.

High Engineer only £120-£240

Parts commonly replaced

  • Flow switch
  • Hydraulic pressure sensor
  • Wiring harness

Related codes

Full explanation for 164
166

Your boiler has detected an issue with how it moves air and waste gases through the system, causing it to shut down for safety.

High Engineer only £100-220

Parts commonly replaced

  • Air Pressure Switch
  • Venturi Tube
  • Fan Assembly

Related codes

Full explanation for 166
270

Your boiler has detected that it is running without enough water inside, causing it to overheat rapidly to protect the internal components.

High DIY-safe £100-350

What to check first

  1. Check the pressure gauge on the front of the boiler; if it is below 1 bar, the system needs topping up.
  2. Use the filling loop underneath the boiler to increase the pressure to between 1 and 1.5 bar.
  3. Attempt to reset the boiler by turning the selector switch to the 'R' position for five seconds.
  4. Ensure all radiator valves are open and not stuck shut.

Parts commonly replaced

  • Circulating Pump
  • Main Heat Exchanger
  • NTC Temperature Sensor

Related codes

Full explanation for 270
432

Your boiler has detected an electrical safety issue where the system is not properly grounded.

Medium Engineer only £100-220

Parts commonly replaced

  • Wiring harness
  • Main PCB
  • Earthing wire

Related codes

Full explanation for 432
433

Your boiler has shut down because it has detected that the water inside is becoming dangerously hot, likely due to a circulation problem.

High DIY-safe £120-£350

What to check first

  1. Ensure all radiator valves are fully open to allow water to flow.
  2. Check that your system water pressure is between 1.0 and 1.5 bar on the gauge.
  3. Gently bleed air from your radiators using a radiator key.
  4. Try resetting the boiler using the selector switch.

Parts commonly replaced

  • Circulating Pump
  • Central Heating Filter (Cleaning)
  • Main Heat Exchanger
  • Overheat Thermostat

Related codes

Full explanation for 433
E.00 – .04

Your boiler has detected a problem with the internal sensor that monitors water returning to the unit, preventing it from heating up correctly.

High Engineer only £90-160

Parts commonly replaced

  • Return temperature sensor (NTC)
  • Sensor wiring harness
Full explanation for E.00 – .04
E.00 – .05

Your boiler has stopped working because it cannot correctly detect the temperature of the water coming back from your radiators.

High Engineer only £90-160

Parts commonly replaced

  • Return temperature sensor (NTC thermistor)
  • Sensor wiring harness

Related codes

Full explanation for E.00 – .05
E.01 – .02

Your boiler has detected that the water coming back from your radiators is hotter than the water going out, which usually means the temperature sensors are confused or water isn't flowing correctly.

High Engineer only £90-180

Parts commonly replaced

  • NTC Temperature Sensor
  • Circulation Pump
  • Flow/Return Thermistor
Full explanation for E.01 – .02
E.01 – .04

Your boiler is struggling to keep a flame lit during operation and has shut down after multiple failed attempts to stay running.

High DIY-safe £100-£280

What to check first

  1. Check that your gas pre-payment meter (if applicable) has credit.
  2. Verify that other gas appliances, like a hob, are working correctly.
  3. Ensure the external condensate pipe has not frozen if the weather is extremely cold.

Parts commonly replaced

  • Flame Sensing Electrode
  • Gas Valve
  • Ignition Lead

Related codes

Full explanation for E.01 – .04
Showing 41–50 of 129
E.01 – .11

Your boiler's fan isn't spinning at the right speed to safely clear exhaust fumes, possibly due to a strong gust of wind or an internal part failure.

High Engineer only £150-350

Parts commonly replaced

  • Fan motor
  • Air pressure switch
  • Main PCB

Related codes

Full explanation for E.01 – .11
E.01 – .12

Your boiler has detected that the water coming back from your radiators is hotter than the water going out, which usually means there is a blockage or a circulation problem preventing heat from escaping the system.

High DIY-safe £100-£250

What to check first

  1. Turn the selector switch to the 'R' (Reset) position for at least five seconds and release.
  2. Ensure all radiator valves are fully open to allow water to circulate.
  3. Check that your central heating pump is running and not making unusual noises.

Parts commonly replaced

  • Return NTC Temperature Sensor
  • Flow NTC Temperature Sensor
  • Central Heating Pump
Full explanation for E.01 – .12
E.01 – .17

Your boiler has stopped working because water is not moving through the system properly or a sensor has lost communication with the main control board.

High DIY-safe £100-£280

What to check first

  1. Locate the selector switch on the front of the boiler.
  2. Turn the dial to the 'R' (Reset) position and hold it for at least 5 seconds before releasing it.
  3. Check that your radiator valves are open and your system pressure is between 1 and 1.5 bar.

Parts commonly replaced

  • Temperature Sensor (NTC thermistor)
  • Circulation Pump
  • Wiring Harness
Full explanation for E.01 – .17
E.01 – .20

Your boiler has shut down because it is getting too hot inside, likely due to a lack of water flow or a faulty sensor safety check.

High DIY-safe £120-280

What to check first

  1. Check if your central heating valves are fully open
  2. Ensure your radiator valves are turned to the highest setting
  3. Check the system pressure gauge and top up to 1.5 bar if it is low
  4. Press the 'Reset' button on the front panel

Parts commonly replaced

  • Circulation pump
  • Flue gas NTC sensor
  • Main heat exchanger (de-scaling)

Related codes

Full explanation for E.01 – .20
E.02 – .00

Your boiler is simply letting you know that the reset button was recently held or pressed, and it is performing its restart sequence.

Low DIY-safe

What to check first

  1. Wait up to 60 seconds for the boiler to cycle through its internal checks.
  2. If the code persists, try turning the selector switch to 'Reset' and then back to the 'On' position.
  3. Ensure that any other fault codes that preceded this one are noted if the boiler fails to restart.

Related codes

Full explanation for E.02 – .00
E.02 – .07

Your boiler has stopped working because the water level inside the system has dropped too low to operate safely.

High DIY-safe £0-160

What to check first

  1. Locate the filling loop (usually a silver braided hose with small tap handles) underneath the boiler.
  2. Slowly open both taps to allow water into the system while watching the pressure gauge.
  3. Close both taps tightly once the needle reaches between 1 and 1.5 bar.

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel
  • Pressure sensor

Related codes

Full explanation for E.02 – .07
E.02 – .16

Your boiler's internal computer has suffered an electronic failure or a communication timeout, meaning it can no longer control the heating process.

High Engineer only £220-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Channel Service Unit
Full explanation for E.02 – .16
E.02 – .17

Your boiler has lost the internal connection between its main computer and the system that controls the gas flow, meaning it cannot ignite safely.

High Engineer only £180-350

Parts commonly replaced

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

Related codes

Full explanation for E.02 – .17
E.02 – .19

Your boiler's electronic control board has detected an incorrect internal setting, which often happens after a repair or a power surge.

High Engineer only £100-280

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Selector Switch
Full explanation for E.02 – .19
E.02 – .20

Your boiler's internal control settings have been disrupted, likely due to a configuration error on the main circuit board.

High Engineer only £100-280

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Control Board Jumpers
Full explanation for E.02 – .20
Showing 51–60 of 129
E.02 – .21

Your boiler's internal computer settings have been changed or are not matching the required configuration, preventing it from running correctly.

Medium Engineer only £80-160

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Selector Jumper Pin
Full explanation for E.02 – .21
E.02 – .47

Your boiler is having trouble communicating with external controls like your thermostat or programmer because of a wiring issue.

High Engineer only £90-180

Parts commonly replaced

  • External thermostat
  • Wiring harness
  • Receiver unit

Related codes

Full explanation for E.02 – .47
E.02 – .48

Your boiler is having trouble communicating with your thermostat or remote control system, meaning it cannot receive the command to turn on.

High DIY-safe £60-140

What to check first

  1. Check if your wireless thermostat has run out of batteries and replace them if necessary.
  2. Ensure the thermostat or programmer is within range of the boiler and hasn't been moved too far away.
  3. Try resetting the boiler and the external control unit to trigger a fresh attempt at pairing.

Parts commonly replaced

  • Wireless thermostat
  • RF receiver unit
  • PCB communication module
Full explanation for E.02 – .48
E.04 – .00

Your boiler has stopped working because it cannot communicate with the internal valve that controls the gas supply.

High Engineer only £180-£350

Parts commonly replaced

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

Related codes

Full explanation for E.04 – .00
E.04 – .01

Your boiler's internal thermometer has developed a fault or loose connection, preventing the system from accurately measuring water temperature and causing it to shut down for safety.

High Engineer only £90-160

Parts commonly replaced

  • Flow Temperature Sensor (NTC Thermistor)
  • Wiring Harness

Related codes

Full explanation for E.04 – .01
E.04 – .02

Your boiler has stopped working 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
Full explanation for E.04 – .02
E.04 – .03

Your boiler has shut down because it is overheating, usually because water isn't moving through the system properly.

High DIY-safe £150-£350

What to check first

  1. Check that the boiler pressure is between 1 and 1.5 bar on the gauge
  2. Ensure all radiator valves and isolation valves are fully open
  3. Try bleeding your radiators to remove trapped air
  4. Reset the boiler using the selector switch

Parts commonly replaced

  • Circulating Pump
  • Main Heat Exchanger
  • Overheat Thermostat

Related codes

Full explanation for E.04 – .03
E.04 – .04

Your boiler has detected a problem with the sensor that monitors exhaust gases and has shut down for safety.

High Engineer only £90-180

Parts commonly replaced

  • Flue Temperature Sensor (NTC)
  • Wiring Harness
  • Main PCB

Related codes

Full explanation for E.04 – .04
E.04 – .05

Your boiler has detected an issue with the sensor that monitors the safety of exhaust gases, causing the system to shut down for protection.

High Engineer only £90-180

Parts commonly replaced

  • Flue Temperature Sensor (NTC)
  • Wiring Harness
  • Main Control Board
Full explanation for E.04 – .05
E.04 – .06

Your boiler has shut down because it is getting too hot inside, which is likely caused by water not moving through the system or a blocked vent.

High Engineer only £120-350

Parts commonly replaced

  • Circulation pump
  • Flue Thermistor (NTC)
  • Heat Exchanger

Related codes

Full explanation for E.04 – .06
Showing 61–70 of 129
E.04 – .08

Your boiler has reached an unsafe temperature and has shut down as a safety precaution, often because water is not moving through the system properly.

High DIY-safe £100-£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 on the gauge
  3. Check for any frozen external pipes if the weather is very cold
  4. Try resetting the boiler following the manufacturer instructions

Parts commonly replaced

  • Circulation Pump
  • Overheat Thermostat
  • NTC Temperature Sensor

Related codes

Full explanation for E.04 – .08
E.04 – .10

Your boiler is trying to start up but cannot ignite the flame, which usually means it isn't getting the gas it needs or the ignition spark is failing.

High DIY-safe £100-£250

What to check first

  1. Check if other gas appliances in your home, like a hob, are working to confirm your gas supply is active.
  2. If you have a prepayment meter, check that you have sufficient credit.
  3. Press and hold the reset button for five seconds to see if the boiler restarts.

Parts commonly replaced

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

Related codes

Full explanation for E.04 – .10
E.04 – .12

Your boiler thinks a flame is present when there shouldn't be one, or the internal burning process is becoming unstable and too hot.

Emergency Engineer only £120-£350

Parts commonly replaced

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

Related codes

Full explanation for E.04 – .12
E.04 – .13

Your boiler has detected that the fan, which safely removes waste gases from the system, has stopped turning or is not communicating correctly with the main control board.

High Engineer only £180-£350

Parts commonly replaced

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

Related codes

Full explanation for E.04 – .13
E.04 – .17

Your boiler has detected a serious internal problem with how it manages gas and air for the burner, meaning it cannot safely light and has locked itself out.

High Engineer only £220-450

Parts commonly replaced

  • Gas Valve
  • Printed Circuit Board (PCB)
  • Fan Assembly
Full explanation for E.04 – .17
E0

Your boiler's internal thermometer has stopped working correctly, meaning the system can't tell how hot the water is and has shut down for safety.

High Engineer only £90-160

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring harness

Related codes

Full explanation for E0
E1

Your boiler has become too hot and has shut down as a safety precaution to prevent damage.

High DIY-safe £120-300

What to check first

  1. Turn off the boiler and allow it to cool down for at least 20 minutes.
  2. Check all radiator valves are open and bleed any air from the radiators using a radiator key.
  3. Check the boiler pressure gauge and top up to 1.5 bar if it is too low.
  4. Reset the boiler using the selector switch.

Parts commonly replaced

  • Overheat Thermostat
  • Circulating Pump
  • Heat Exchanger

Related codes

Full explanation for E1
E2

Your boiler is struggling to move water around the system, possibly because of trapped air or a blockage.

High DIY-safe £100-£250

What to check first

  1. Turn off your heating and let the radiators cool down.
  2. Use a radiator key to bleed any trapped air from your radiators.
  3. Check your boiler pressure gauge and top it up to between 1 and 1.5 bar if it has dropped.

Parts commonly replaced

  • Circulation Pump
  • Heat Exchanger
  • Pressure Sensor

Related codes

Full explanation for E2
E3

Your boiler's internal computer has developed a fault and can no longer control the heating system safely.

High Engineer only £280-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness
Full explanation for E3
E4

Your boiler has failed to light the flame after several attempts, which has caused it to shut down for safety.

High DIY-safe £120-300

What to check first

  1. Check that your gas supply is turned on at the meter
  2. Press and hold the reset button for five seconds
  3. Bleed your radiators to remove trapped air from the system

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

Full explanation for E4
Showing 71–80 of 129
E09

Your boiler has stopped working because it cannot communicate with the gas control system, meaning it cannot safely ignite to provide heat or hot water.

High Engineer only £120-280

Parts commonly replaced

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

Related codes

Full explanation for E09
E10

Your boiler is having trouble communicating with the optional sensor used to measure the temperature outside.

Low DIY-safe £60-140

What to check first

  1. Check if any external wires leading to a small box on your outside wall are visibly damaged or loose
  2. Turn the boiler mode selector to 'Reset' for five seconds and then back to its original position
  3. If the fault persists, contact an engineer to inspect the sensor wiring or disable the sensor in the boiler settings

Parts commonly replaced

  • Outdoor weather compensation sensor
  • Low voltage signal wiring

Related codes

Full explanation for E10
E12

Your boiler has detected that water isn't moving through the system correctly, which is preventing it from firing up safely.

High DIY-safe £100-£250

What to check first

  1. Check that your system pressure is between 1.0 and 1.5 bar on the pressure gauge
  2. Ensure all radiator valves and isolation valves under the boiler are fully open
  3. Bleed your radiators to remove any trapped air that might be blocking flow
  4. Reset the boiler using the selector switch

Parts commonly replaced

  • Differential pressure switch
  • Pump
  • Diaphragm
  • Flow pipe microswitch

Related codes

Full explanation for E12
E13

Your boiler thinks water is moving through the system even when the pump is off, which prevents it from starting its next cycle safely.

High Engineer only £100-£220

Parts commonly replaced

  • Flow switch diaphragm
  • Differential pressure switch
  • Microswitch

Related codes

Full explanation for E13
E15

Your boiler has detected an electrical communication problem with the gas valve, meaning it cannot safely release fuel to start the flame.

High Engineer only £180-350

Parts commonly replaced

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

Related codes

Full explanation for E15
E20

Your boiler's temperature sensor has developed a fault or is incorrectly reporting the temperature of the water in your radiators.

High Engineer only £90-160

Parts commonly replaced

  • Central heating NTC thermistor
  • Wiring harness

Related codes

Full explanation for E20
E28

Your boiler has detected an issue with how it clears waste gases or condensation, causing it to shut down for safety.

High Engineer only £100-£280

Parts commonly replaced

  • Flue NTC Sensor
  • Air Pressure Switch
  • Condensate Trap

Related codes

Full explanation for E28
E40

Your boiler has stopped working because the sensor that monitors the temperature of the water returning from your radiators has developed a fault or disconnected.

High Engineer only £90-160

Parts commonly replaced

  • Return NTC thermistor
  • Connecting wiring harness

Related codes

Full explanation for E40
E50

Your boiler's temperature sensor for hot water has stopped working properly, meaning you may experience fluctuating water temperatures or no hot water at all.

Medium Engineer only £90-160

Parts commonly replaced

  • Hot water NTC thermistor
  • Wiring harness / Connector

Related codes

Full explanation for E50
E53

Your boiler is not burning gas correctly because the exhaust pipe on the outside of your house might be obstructed.

Emergency DIY-safe £80-250

What to check first

  1. Check the external flue terminal for any visible obstructions such as bird nests, leaves, or debris
  2. Carefully remove any external blockages if it is safe to reach from ground level
  3. Ensure the flue terminal is not covered by garden furniture or building materials
  4. Do not attempt to open the boiler; if no external blockage is found, call a Gas Safe engineer

Parts commonly replaced

  • Flue seals
  • Gas valve
  • Fan assembly

Related codes

Full explanation for E53
Showing 81–90 of 129
E54

Your boiler is struggling to detect when you turn on your hot taps, meaning you may experience cold water or intermittent temperatures.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW Flow Sensor
  • Flow Turbine
  • Wiring harness

Related codes

Full explanation for E54
E55

Your boiler's electronic control board needs to be synchronised with the gas valve to ensure it is burning fuel efficiently and safely.

High Engineer only £100-250

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Gas Valve

Related codes

Full explanation for E55
E78

Your boiler has lost its ability to accurately measure the water pressure, which means it will stop working as a safety precaution.

High Engineer only £120-190

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness

Related codes

Full explanation for E78
E83/E84/E85/E86/E87

Your boiler’s internal control parts are having trouble talking to each other, which means the system has stopped working to protect itself.

High Engineer only £180-£450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness
  • Display Interface Module
Full explanation for E83/E84/E85/E86/E87
E92

Your boiler has detected an issue with the air and gas mixture while trying to automatically calibrate its combustion levels.

High Engineer only £100-£350

Parts commonly replaced

  • Electrode set
  • Gas valve
  • PCB
  • Flue seals

Related codes

Full explanation for E92
E100

Your boiler's internal computer has lost track of the time or date, which is preventing it from running its programmed schedule.

Medium DIY-safe £0-120

What to check first

  1. Locate the clock or timer interface on the front of the boiler
  2. Follow the manual to reset the current time and date
  3. Press the Reset button for 5 seconds to clear the error code

Parts commonly replaced

  • External Timer Unit
  • Printed Circuit Board (PCB)
Full explanation for E100
E109

Your boiler is not moving water around the system correctly, causing it to shut down to prevent overheating.

High DIY-safe £150-£350

What to check first

  1. Check if the pressure gauge is below 1.0 bar and top it up using the filling loop
  2. Ensure all radiator valves are fully open
  3. Bleed any air out of your radiators using a radiator key

Parts commonly replaced

  • Circulation pump
  • Main heat exchanger
  • Flow temperature sensor

Related codes

Full explanation for E109
E110

Your boiler has likely overheated, causing a safety sensor to automatically shut the system down to prevent damage.

High DIY-safe £90-220

What to check first

  1. Check that your radiator valves are open and not turned off.
  2. Ensure your system water pressure is between 1.0 and 1.5 bar on the gauge.
  3. Wait for the boiler to cool down, then turn the selector switch to the 'R' (Reset) position for at least five seconds.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Temperature NTC Sensor

Related codes

Full explanation for E110
E117

Your boiler has detected that there is too much water pressure in the system, which can cause it to shut down for safety.

Medium DIY-safe £0-120

What to check first

  1. Check that the filling loop valves under the boiler are fully closed
  2. Identify the radiator furthest from the boiler or a towel rail with a bleed valve
  3. Using a radiator key, carefully bleed water (not just air) from the radiator into a container until the boiler pressure gauge drops into the green zone (typically 1.0 to 1.5 bar)

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel re-pressurisation
  • Pressure relief valve

Related codes

Full explanation for E117
E118

Your boiler has stopped working because the water pressure in the system has dropped too low and needs to be topped up.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver braided hose under the boiler).
  2. Slowly open the one or two taps/levers on the filling loop until you hear water moving.
  3. Watch the pressure gauge and close the taps firmly once it reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel
  • Pressure sensor

Related codes

Full explanation for E118
Showing 91–100 of 129
E119

Your boiler has stopped working because the water pressure is too low and needs to be topped up.

High DIY-safe £0-160

What to check first

  1. Locate the filling loop, which is usually a flexible silver hose underneath the boiler.
  2. Slowly open both taps on the filling loop until you hear water flowing.
  3. Watch the pressure gauge and close the taps once the needle reaches between 1 and 1.5 bar.

Parts commonly replaced

  • Water pressure switch
  • Expansion vessel repressurisation
  • Filling loop

Related codes

Full explanation for E119
E125

Your boiler has detected that water is not moving around the system correctly, which is causing it to overheat and shut down for safety.

High DIY-safe £180-350

What to check first

  1. Check that all radiator valves are fully open
  2. Check that the boiler pressure is between 1.0 and 1.5 bar on the gauge
  3. Gently bleed your radiators to remove any trapped air pockets

Parts commonly replaced

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

Related codes

Full explanation for E125
E128

Your boiler is struggling to keep its burner lit and has automatically shut down after failing to maintain a flame multiple times.

High Engineer only £100-£250

Parts commonly replaced

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

Related codes

Full explanation for E128
E129

Your boiler is struggling to keep a steady flame alight and has failed to automatically adjust itself to the correct setting.

High Engineer only £120-280

Parts commonly replaced

  • Flame sensing electrode
  • Ignition lead
  • Gas valve

Related codes

Full explanation for E129
E130

Your boiler has detected that the exhaust gases are getting too hot, causing it to shut down as a safety precaution.

High Engineer only £100-220

Parts commonly replaced

  • Flue NTC Sensor
  • Main Heat Exchanger
  • Wiring Harness

Related codes

Full explanation for E130
E131

Your boiler has shut down because it detected that the exhaust gases are getting too hot, which is a safety mechanism to prevent damage.

High Engineer only £120-350

Parts commonly replaced

  • Flue Overheat Thermostat
  • Heat Exchanger
  • Main PCB

Related codes

Full explanation for E131
E133

Your boiler has failed to ignite, which means it cannot provide the heat or hot water you need.

High DIY-safe £100-£350

What to check first

  1. Check if your gas meter has credit and the gas emergency valve is open.
  2. Try to reset the boiler by turning the selector knob to the 'R' position for at least five seconds.
  3. If it is freezing outside, check if your white plastic condensate pipe is blocked with ice.

Parts commonly replaced

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

Related codes

Full explanation for E133
E134

Your boiler has tried to ignite several times but cannot detect a flame, likely due to an issue with the gas supply or the ignition process.

High DIY-safe £100-350

What to check first

  1. Check that your gas emergency control valve is open and you have credit on your meter.
  2. Check if other gas appliances in your home, such as a hob, are working correctly.
  3. Press and hold the reset button for five seconds to see if the boiler restarts.

Parts commonly replaced

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

Related codes

Full explanation for E134
E135

Your boiler has lost its gas supply or detected a technical fault with the gas valve, meaning it cannot ignite to provide heating or hot water.

High DIY-safe £150-350

What to check first

  1. Check if other gas appliances, like a cooker, are working to confirm gas is reaching the property.
  2. Ensure your gas meter has credit if you use a prepay system.
  3. Reset the boiler by turning the selector switch to the 'R' position for five seconds.

Parts commonly replaced

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

Related codes

Full explanation for E135
E154

Your boiler has detected that the water temperature readings are inconsistent, which usually means the water isn't circulating properly or a sensor has failed.

High Engineer only £90-180

Parts commonly replaced

  • Flow temperature sensor
  • Return temperature sensor
  • Circulation pump

Related codes

Full explanation for E154
Showing 101–110 of 129
E160

Your boiler has stopped working because the fan that helps remove waste gases is either faulty or not receiving power.

High Engineer only £180-350

Parts commonly replaced

  • Fan motor
  • PCB
  • Fan wiring harness

Related codes

Full explanation for E160
E160 / E161

Your boiler has detected a problem with the fan that safely removes exhaust gases, meaning the system has shut down to prevent damage or unsafe operation.

High Engineer only £250-£450

Parts commonly replaced

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

Related codes

Full explanation for E160 / E161
E163

Your boiler's temperature sensor for hot water has developed a fault or a loose connection, meaning it cannot accurately tell how hot the water is.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW NTC Thermistor Sensor
  • Connecting Wiring Loom

Related codes

Full explanation for E163
E164

Your boiler is struggling to accurately measure its internal water pressure, which prevents it from running safely.

High Engineer only £130-£220

Parts commonly replaced

  • Water pressure sensor (Transducer)
  • Wiring harness to sensor
  • Main PCB

Related codes

Full explanation for E164
E167

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)

Related codes

Full explanation for E167
E168

Your boiler's electronic control centre has encountered an internal error and has stopped working to protect itself.

High DIY-safe £250-450

What to check first

  1. Turn the selector switch to the 'Reset' position and hold for five seconds
  2. Switch the main electrical power supply to the boiler off and back on again
  3. Check if any other household appliances have caused a power surge or trip in your fuse box

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External Surge Protector

Related codes

Full explanation for E168
E193

Your boiler has detected that water is not circulating correctly through the system before the burner ignites, often caused by a buildup of air or a blockage.

High DIY-safe £100-£350

What to check first

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

Parts commonly replaced

  • Circulation Pump
  • Automatic Air Vent
  • Flow Temperature Sensor

Related codes

Full explanation for E193
E270

Your boiler has detected that water isn't moving through the system properly, causing it to overheat quickly to protect internal components.

High DIY-safe £120-350

What to check first

  1. Check that the boiler pressure is between 1.0 and 1.5 bar on the pressure gauge.
  2. Ensure all radiator valves and isolation valves under the boiler are fully open.
  3. Bleed your radiators to remove any trapped air pockets that might be blocking flow.

Parts commonly replaced

  • Circulation pump
  • Main heat exchanger
  • Overheat thermostat

Related codes

Full explanation for E270
E317

Your boiler has detected an issue with the electrical power timing coming into the unit, which is preventing it from running safely.

High Engineer only £150-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Voltage Regulator

Related codes

Full explanation for E317
E321

Your boiler's hot water sensor has failed or is giving an incorrect reading, which means the system cannot accurately heat your tap water.

Medium Engineer only £90-160

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC thermistor
  • Wiring harness

Related codes

Full explanation for E321
Showing 111–120 of 129
E384

Your boiler thinks it sees a flame even though it hasn't started the ignition process yet, which is causing it to shut down for safety.

High Engineer only £120-280

Parts commonly replaced

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

Related codes

Full explanation for E384
E385

Your boiler is not receiving the correct amount of electrical power from your home supply to run safely and correctly.

Medium DIY-safe £100-280

What to check first

  1. Check if there is a power cut or if other appliances in your home are flickering
  2. Ensure the boiler's fused spur switch is fully turned on
  3. Check your consumer unit (fuse box) to see if a circuit breaker has tripped

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External Voltage Stabiliser

Related codes

Full explanation for E385
E430

Your boiler has detected that the water pressure is incorrectly set or fluctuates too much, often caused by a temporary drop below the operating level.

Medium DIY-safe £60-140

What to check first

  1. Check the pressure gauge on the front of the boiler
  2. If the needle is below 1 bar, use the filling loop handles underneath to top it up to 1.5 bar
  3. Turn the boiler off and back on to reset the fault

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Water pressure sensor

Related codes

Full explanation for E430
H.01 – .00

Your boiler has lost its connection to the internal gas control system, meaning it cannot safely ignite to provide heating or hot water.

High Engineer only £180-450

Parts commonly replaced

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

Related codes

Full explanation for H.01 – .00
H.01 – .05

Your boiler has detected that water isn't moving through the system correctly or is overheating too quickly, causing it to shut down for safety.

High DIY-safe £100-£350

What to check first

  1. Check that your boiler pressure is between 1 and 1.5 bar on the gauge.
  2. Ensure all radiator valves and isolating valves under the boiler are fully open.
  3. Gently bleed your radiators to remove trapped air that might be blocking water flow.

Parts commonly replaced

  • Circulation pump
  • NTC Temperature Sensors
  • Main Heat Exchanger (if blocked)

Related codes

Full explanation for H.01 – .05
H.01 – .08

Your boiler is overheating because the water inside cannot circulate quickly enough to stay at a safe temperature.

High DIY-safe £120-£350

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the boiler pressure gauge is between 1.0 and 1.5 bar
  3. Bleed any air from your radiators
  4. Restart the boiler using the selector switch

Parts commonly replaced

  • Central heating pump
  • Flow temperature sensor (NTC)
  • Main heat exchanger (flushing/cleaning)

Related codes

Full explanation for H.01 – .08
H.01 – .14

Your boiler has sensed it is getting too hot too quickly, likely because water isn't moving through the system properly.

High DIY-safe £120-£350

What to check first

  1. Check that your system pressure is between 1.0 and 1.5 bar on the pressure gauge.
  2. Ensure all radiator valves and internal stop taps are fully open.
  3. Bleed your radiators to remove any trapped air pockets.
  4. Reset the boiler to see if the temporary fault clears.

Parts commonly replaced

  • Circulation Pump
  • Overheat Thermostat
  • Flow Temperature Sensor
  • Main Heat Exchanger (if blocked)

Related codes

Full explanation for H.01 – .14
H.01 – .18

Your boiler is struggling to move water around the system, which is preventing it from heating up safely.

High DIY-safe £120-350

What to check first

  1. Check if the central heating valves under the boiler are fully open
  2. Ensure your radiator valves are turned on
  3. Check the system pressure gauge and top it up to 1.5 bar if it is too low
  4. Gently bleed your radiators to remove trapped air

Parts commonly replaced

  • Circulation pump
  • Flow/Return temperature sensors (NTC thermistors)
  • Main heat exchanger (if blocked)

Related codes

Full explanation for H.01 – .18
H.01 – .21

Your boiler is heating up too quickly when you turn on the hot water, causing it to shut down to prevent overheating.

Medium Engineer only £120-280

Parts commonly replaced

  • Plate heat exchanger
  • DHW temperature sensor (NTC)
  • Circulation pump

Related codes

Full explanation for H.01 – .21
H.02 – .02

Your boiler's main control board has lost its internal settings or was not set up correctly, meaning the system doesn't know how to operate.

High Engineer only £180-350

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

Full explanation for H.02 – .02
Showing 121–129 of 129
H.02 – .03

Your boiler's internal computer has become confused about its own settings, often caused by a temporary communication glitch or a power interruption.

High DIY-safe £0-120

What to check first

  1. Locate the selector switch on the front of the boiler control panel.
  2. Turn the switch to the 'R' (Reset) position and hold it for at least five seconds.
  3. Return the switch to its original position and wait for the boiler to restart.

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Interface cable

Related codes

Full explanation for H.02 – .03
H.02 – .04

Your boiler's internal computer is having a temporary glitch or is confused by its own settings, which is preventing it from running properly.

High DIY-safe £100-350

What to check first

  1. Locate the selector switch on the front of the boiler control panel.
  2. Turn the switch to the 'R' (Reset) position and hold it for at least 5 seconds.
  3. Return the switch to its original position (Heating or Hot Water) and wait for the boiler to restart.

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Parameter Plug

Related codes

Full explanation for H.02 – .04
H.02 – .06

Your boiler has detected that the water pressure is incorrect or is fluctuating due to a possible leak in the system.

High DIY-safe £80-250

What to check first

  1. Check the pressure gauge on the front of the boiler; it should ideally be between 1 and 1.5 bar.
  2. Inspect visible radiator valves, pipework, and the boiler for any signs of water leaks.
  3. If the pressure is low, use the filling loop to carefully top up the system water pressure.

Parts commonly replaced

  • Water Pressure Sensor
  • Expansion Vessel
  • Filling Loop Valve
  • Automatic Air Vent

Related codes

Full explanation for H.02 – .06
H.03 -.00

Your boiler is struggling to read information from its internal temperature sensors, which is preventing it from heating up correctly.

High Engineer only £90-180

Parts commonly replaced

  • Central Heating NTC Sensor
  • Hot Water NTC Sensor
  • Flue Thermistor

Related codes

Full explanation for H.03 -.00
H.03 – .01

Your boiler's internal computer is having trouble talking to its other components, which has caused the system to stop working for safety.

High Engineer only £280-550

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

Full explanation for H.03 – .01
H.03 – .02

Your boiler has lost its flame while it was running, meaning it has shut down as a safety precaution because it can no longer heat your water or radiators.

High Engineer only £120-300

Parts commonly replaced

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

Related codes

Full explanation for H.03 – .02
OFF OFF OFF

Your boiler has no electrical power, meaning the display is blank and the unit cannot operate.

High DIY-safe £60-250

What to check first

  1. Check if the boiler is switched on at the wall socket or isolation switch
  2. Check your home's main consumer unit (fuse box) to see if a circuit breaker has tripped
  3. Replace the 3-amp fuse in the boiler's fused spur switch

Parts commonly replaced

  • Fused spur (3A)
  • Printed Circuit Board (PCB)
  • Display interface

Related codes

Full explanation for OFF OFF OFF
ON OFF ON

Your boiler has failed to light the gas flame successfully and has shut down as a safety precaution.

High DIY-safe £100-350

What to check first

  1. Check that your gas pre-payment meter (if you have one) has sufficient credit.
  2. Ensure other gas appliances, like a hob, are working to confirm gas supply to the property.
  3. Turn the selector switch to the 'R' (Reset) position for five seconds, then release it back to the 'On' position.

Parts commonly replaced

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

Related codes

Full explanation for ON OFF ON
ON ON ON

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

High Engineer only £120-280

Parts commonly replaced

  • Wiring harness
  • Printed Circuit Board (PCB)
Full explanation for ON ON ON