BoilerFaultCodes 1 green flash
Your boiler has reached its set temperature and is temporarily pausing its burner; this is a completely normal part of its operation.
Baxi Netaheat Fault codes & diagnostics
129 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Regular Natural Gas 9-23 kW 1978-1996 Discontinued
Replaced by: Potterton Profile
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
114 High
6 Medium
7 Low
Just want the most common Baxi Netaheat 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 red flash Your boiler has detected that it is getting too hot or the water isn't moving through the system properly, causing it to shut down for safety.
Your boiler has detected that it is getting too hot or the water isn't moving through the system properly, causing it to shut down for safety.
What to check first
- Check that your radiator valves are open
- Ensure the system pressure is between 1 and 1.5 bar on the gauge
- Try resetting the boiler using the dial or reset button
Parts commonly replaced
- Temperature Sensor (NTC Thermistor)
- Circulation Pump
- Overheat Thermostat
Related codes
2 red flashes Your boiler has become too hot and has automatically shut itself down to prevent damage.
Your boiler has become too hot and has automatically shut itself down to prevent damage.
What to check first
- Turn off the boiler at the main electrical switch and wait 15 minutes for it to cool down.
- Check that your radiator valves are open and that there is enough water pressure in the system.
- Press the reset button firmly; if the red light persists or recurs, you must call a professional.
Parts commonly replaced
- Overheat Thermostat
- Circulation Pump
- Thermistor
Related codes
3 green flashes Your boiler has lost its flame briefly and will try to restart itself, but it may be struggling to keep the burner lit.
Your boiler has lost its flame briefly and will try to restart itself, but it may be struggling to keep the burner lit.
What to check first
- Check that your gas supply is turned on (check other gas appliances)
- Press the reset button once the boiler stops attempting to restart
- Monitor the boiler to see if the fault progresses to a solid red light
Parts commonly replaced
- Flame sense electrode
- Gas valve
- PCB
Related codes
3 red flashes Your boiler has tried to light several times but cannot start up, meaning you currently have no heating or hot water.
Your boiler has tried to light several times but cannot start up, meaning you currently have no heating or hot water.
What to check first
- Check that your gas pre-pay meter is in credit
- Ensure any gas isolation valves are turned to the 'on' position
- Press and hold the reset button for five seconds to restart the ignition sequence
Parts commonly replaced
- Ignition electrode
- Flame sensing probe
- Gas valve
Related codes
4 green flashes Your boiler has experienced a brief communication hiccup between its internal electronic parts and should fix itself automatically.
Your boiler has experienced a brief communication hiccup between its internal electronic parts and should fix itself automatically.
What to check first
- Wait for the boiler to self-reset automatically
- Monitor the display to see if the flashes stop
- If the lights persist, turn the power to the boiler off and back on once
Parts commonly replaced
- None (Software reset)
- Printed Circuit Board (PCB)
Related codes
4 red flashes Your boiler has detected that the internal fan, which clears waste gases out of the flue, is not spinning correctly or has lost power.
Your boiler has detected that the internal fan, which clears waste gases out of the flue, is not spinning correctly or has lost power.
Parts commonly replaced
- Fan assembly
- Air pressure switch
- PCB (Control board)
Related codes
5 green flashes Your boiler has experienced a brief electronic 'hiccup' or data error and is trying to correct itself automatically.
Your boiler has experienced a brief electronic 'hiccup' or data error and is trying to correct itself automatically.
What to check first
- Wait up to 10 minutes for the boiler to automatically reset itself.
- If the flashing continues, turn the power switch to the boiler off and then back on again.
- Ensure there are no external electrical appliances causing interference near the boiler.
Parts commonly replaced
- Printed Circuit Board (PCB)
Related codes
5 red flashes Your boiler's internal memory unit has developed a communication fault, meaning the control board no longer knows how to operate the system safely.
Your boiler's internal memory unit has developed a communication fault, meaning the control board no longer knows how to operate the system safely.
Parts commonly replaced
- Parameter Storage Unit (PSU)
- Main Control PCB
Related codes
6 green flashes Your boiler has encountered a minor temporary glitch and is currently pausing before trying to restart itself automatically.
Your boiler has encountered a minor temporary glitch and is currently pausing before trying to restart itself automatically.
What to check first
- Wait for the boiler to complete its automatic self-reset cycle
- If the error persists, turn the boiler power switch off and back on again
- Monitor the display to see if the flashing returns
Parts commonly replaced
- Control Board (PCB)
- External Wiring
Related codes
Showing 11–20 of 129
6 red flashes Your boiler has encountered a general electronic fault and needs to be reset to try and clear the error.
Your boiler has encountered a general electronic fault and needs to be reset to try and clear the error.
What to check first
- Locate the reset button or selector switch on the front control panel
- Turn the selector to the reset position and hold for 5 seconds
- Release the switch and wait for the boiler to attempt a restart
Parts commonly replaced
- Printed Circuit Board (PCB)
- Wiring harness
Related codes
FLASH FLASH ON Your boiler's fan, which safely pushes exhaust gases out of your home, has stopped working properly, preventing the heating from starting up for safety reasons.
Your boiler's fan, which safely pushes exhaust gases out of your home, has stopped working properly, preventing the heating from starting up for safety reasons.
Parts commonly replaced
- Fan assembly
- Air pressure switch
- PCB (Control board)
Related codes
FLASH OFF FLASH Your boiler has detected that the electrical supply coming into the unit is too low for it to operate safely.
Your boiler has detected that the electrical supply coming into the unit is too low for it to operate safely.
What to check first
- Check if there is a regional power cut or 'brownout' in your local area
- Ensure the boiler is plugged directly into its fused spur and not an extension lead
- Check your property's consumer unit (fuse box) for any tripped switches
Parts commonly replaced
- Printed Circuit Board (PCB)
- External Voltage Regulator
Related codes
FLASH OFF ON Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
What to check first
- Wait at least 15-20 minutes for the unit to cool down completely.
- Ensure all radiator valves and the bypass valve are open to allow water flow.
- Press the reset button or turn the control knob to 'Off' and back to 'On' to restart.
Parts commonly replaced
- Overheat Thermostat
- Pump
- Flow/Return Thermistor
FLASH ON FLASH Your boiler's internal computer has encountered a critical error and can no longer control the heating system safely.
Your boiler's internal computer has encountered a critical error and can no longer control the heating system safely.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Wiring Harness
FLASH ON ON Your boiler's internal computer has developed an electrical fault and is unable to control the heating process.
Your boiler's internal computer has developed an electrical fault and is unable to control the heating process.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Control Box
Related codes
ON FLASH FLASH Your boiler is overheating because water isn't moving through the system properly or there isn't enough water inside the unit.
Your boiler is overheating because water isn't moving through the system properly or there isn't enough water inside the unit.
What to check first
- Check if your radiator valves are open
- Ensure your external pump is running if visible
- Check that your header tank has water (if it is an open-vented system)
Parts commonly replaced
- External Circulation Pump
- Overheat Thermostat
- Flow Switch
Related codes
ON FLASH ON Your boiler has detected a problem with its internal temperature sensors, which means it cannot tell if the water is too hot or too cold.
Your boiler has detected a problem with its internal temperature sensors, which means it cannot tell if the water is too hot or too cold.
Parts commonly replaced
- NTC Thermistor
- Wiring Harness
- Control Board
Related codes
ON OFF FLASH Your boiler has detected that the electrical wiring coming from your home's power supply is connected the wrong way around, which is a safety risk.
Your boiler has detected that the electrical wiring coming from your home's power supply is connected the wrong way around, which is a safety risk.
Parts commonly replaced
- External wiring connections
- Printed Circuit Board (PCB)
ON ON FLASH Your boiler's internal computer has developed a fault and can no longer control the heating system safely.
Your boiler's internal computer has developed a fault and can no longer control the heating system safely.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Control Box
Related codes
Digital codes
110 Your boiler has become too hot and has shut down as a safety precaution to prevent damage.
Your boiler has become too hot and has shut down as a safety precaution to prevent damage.
What to check first
- Turn off the boiler and allow it to cool completely
- Check all radiator valves are open
- Bleed your radiators to remove trapped air
- Check the system pressure and top up if it is below 1.0 bar
- Press the reset button on the boiler
Parts commonly replaced
- Overheat Thermostat
- Circulation Pump
- Temperature Sensors (NTC)
Related codes
117 Your boiler has too much water inside it, which puts extra stress on the system and has caused it to stop working for safety.
Your boiler has too much water inside it, which puts extra stress on the system and has caused it to stop working for safety.
What to check first
- Check that the filling loop valves are fully closed and not leaking water into the system
- Bleed water from a radiator using a bleed key to reduce the system pressure
- Monitor the pressure gauge until it returns to around 1.0 to 1.5 bar
- Reset the boiler once the pressure is within the normal operating range
Parts commonly replaced
- Expansion Vessel
- Pressure Relief Valve (PRV)
- Filling Loop
Related codes
118 Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
What to check first
- Locate the filling loop (usually a silver braided hose with small tap handles) underneath or near the boiler.
- Slowly open both taps until you hear water entering the system.
- Watch the pressure gauge and close both taps tightly once the needle reaches between 1.0 and 1.5 bar.
Parts commonly replaced
- Filling loop valve
- Pressure sensor
- Expansion vessel
Related codes
119 Your boiler has stopped working because the water pressure in your heating system has dropped below the minimum level required to run safely.
Your boiler has stopped working because the water pressure in your heating system has dropped below the minimum level required to run safely.
What to check first
- Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.
- Slowly open the tap or lever until you hear water flowing and watch the pressure gauge.
- Close the tap tightly once the gauge reaches between 1 and 1.5 bar.
Parts commonly replaced
- Filling loop
- Expansion vessel
- Pressure sensor
Related codes
125 Your boiler is struggling to move water through the system, which is causing it to overheat and shut down for safety.
Your boiler is struggling to move water through the system, which is causing it to overheat and shut down for safety.
What to check first
- Check that your radiators are bled and all valves are fully open
- Ensure your system pressure is topped up to between 1.0 and 1.5 bar
- Check for any frozen pipes if it is currently mid-winter
Parts commonly replaced
- Circulation pump
- Flow temperature sensor
- Heat exchanger
Related codes
127 Your boiler hasn't been able to heat the water hot enough to safely kill off any potential bacteria in the system.
Your boiler hasn't been able to heat the water hot enough to safely kill off any potential bacteria in the system.
What to check first
- Check that your hot water timer is set to be on for at least one hour to allow it to reach temperature
- Ensure your hot water temperature dial or cylinder thermostat is not set too low (should be at least 60°C)
- Check if you have used a large amount of hot water just before the scheduled anti-bacteria cycle
Parts commonly replaced
- Cylinder NTC sensor
- Immersion heater
- Three-way diverter valve
Related codes
128 Your boiler started to heat up but the flame went out unexpectedly while it was running.
Your boiler started to heat up but the flame went out unexpectedly while it was running.
Parts commonly replaced
- Flame sensing electrode
- Gas valve
- PCB (Printed Circuit Board)
- Condensate trap
Related codes
133 Your boiler is failing to light the gas or stay lit, which is preventing your heating and hot water from working.
Your boiler is failing to light the gas or stay lit, which is preventing your heating and hot water from working.
What to check first
- Check that your gas prepay meter has credit
- Ensure other gas appliances in your home are working
- Press and hold the reset button for five seconds
Parts commonly replaced
- Ignition lead
- Flame sensing electrode
- Gas valve
- Spark generator
Related codes
153 Your boiler has been manually reset after a previous fault and is now attempting to restart its normal operation.
Your boiler has been manually reset after a previous fault and is now attempting to restart its normal operation.
What to check first
- Press and hold the reset button for at least 5 seconds
- Switch the main electrical power to the boiler off and back on again
- Check that any external thermostats or timers are calling for heat
Parts commonly replaced
- No parts usually required
- Printed Circuit Board (PCB)
160 Your boiler has stopped working because the fan that clears away waste gases is not spinning or communicating correctly with the system.
Your boiler has stopped working because the fan that clears away waste gases is not spinning or communicating correctly with the system.
Parts commonly replaced
- Fan assembly
- Printed Circuit Board (PCB)
- Wiring harness
Related codes
Showing 31–40 of 129
162 The boiler is unable to safely clear exhaust fumes, so it has shut down to prevent waste gases from entering your home.
The boiler is unable to safely clear exhaust fumes, so it has shut down to prevent waste gases from entering your home.
Parts commonly replaced
- Air Pressure Switch
- Venturi Tube
- Fan Assembly
Related codes
164 Your boiler has detected an issue with how water is flowing through the system or a sensor reading, which is preventing it from heating up.
Your boiler has detected an issue with how water is flowing through the system or a sensor reading, which is preventing it from heating up.
Parts commonly replaced
- Water Pressure Sensor
- Flow Switch
- Circulation Pump
Related codes
166 Your boiler has stopped working because it cannot confirm that the fan is blowing safely out of the flue.
Your boiler has stopped working because it cannot confirm that the fan is blowing safely out of the flue.
Parts commonly replaced
- Air Pressure Switch
- Venturi Tube
- Fan
Related codes
270 Your boiler has sensed a rapid rise in temperature because there is not enough water circulating through the heat exchanger to carry the heat away.
Your boiler has sensed a rapid rise in temperature because there is not enough water circulating through the heat exchanger to carry the heat away.
What to check first
- Check the system pressure gauge and top it up to 1.5 bar if it is low
- Ensure all radiator valves and boiler isolation valves are fully open
- Bleed all radiators to remove trapped air pockets that might block water flow
Parts commonly replaced
- Circulating Pump
- Temperature Sensors (NTC Thermistors)
- Primary Heat Exchanger
Related codes
432 Your boiler has detected an electrical grounding issue which is preventing it from running safely.
Your boiler has detected an electrical grounding issue which is preventing it from running safely.
Parts commonly replaced
- Earth connection wiring
- Printed Circuit Board (PCB)
- Electrode lead
Related codes
433 Your boiler has shut down because its internal temperature got too hot, likely due to water not circulating through the system properly.
Your boiler has shut down because its internal temperature got too hot, likely due to water not circulating through the system properly.
Parts commonly replaced
- Circulation pump
- Heat exchanger
- Temperature sensor (NTC thermistor)
Related codes
E.00 – .04 Your boiler has lost communication with the sensor that monitors water returning from your radiators, preventing it from heating your home safely.
Your boiler has lost communication with the sensor that monitors water returning from your radiators, preventing it from heating your home safely.
Parts commonly replaced
- Return temperature sensor (NTC thermistor)
- Sensor wiring harness
E.00 – .05 Your boiler has stopped working because it cannot correctly read the temperature of the water returning to the unit due to a sensor connection problem.
Your boiler has stopped working because it cannot correctly read the temperature of the water returning to the unit due to a sensor connection problem.
Parts commonly replaced
- Return temperature sensor (NTC thermistor)
- Sensor wiring harness
E.01 – .02 Your boiler has detected that the water coming back is hotter than the water going out, which usually means the water isn't circulating properly or a sensor has failed.
Your boiler has detected that the water coming back is hotter than the water going out, which usually means the water isn't circulating properly or a sensor has failed.
Parts commonly replaced
- Return thermistor
- Flow thermistor
- Circulation pump
E.01 – .04 Your boiler is repeatedly losing its flame and has locked itself out for safety reasons.
Your boiler is repeatedly losing its flame and has locked itself out for safety reasons.
What to check first
- Check that you have a gas supply to the house (e.g. check a gas cooker)
- Check if your gas meter has credit
- Press the reset button once to see if the boiler restarts
Parts commonly replaced
- Flame sensing electrode
- Gas valve
- PCB
Related codes
Showing 41–50 of 129
E.01 – .11 Your boiler's fan isn't spinning at the right speed to safely clear waste gases, often caused by strong winds blowing into the flue or an internal part failing.
Your boiler's fan isn't spinning at the right speed to safely clear waste gases, often caused by strong winds blowing into the flue or an internal part failing.
Parts commonly replaced
- Fan assembly
- Air pressure switch
- Gas/air valves
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 the water isn't flowing correctly through the system.
Your boiler has detected that the water coming back from your radiators is hotter than the water going out, which usually means the water isn't flowing correctly through the system.
What to check first
- Check that all radiator valves are fully open
- Check that your boiler pressure is between 1 and 1.5 bar
- Press the reset button once to see if the error clears
Parts commonly replaced
- Circulation pump
- Return temperature NTC sensor
- Flow temperature NTC sensor
Related codes
E.01 – .17 Your boiler has stopped working because water is not moving through the system or a sensor is disconnected, preventing it from heating up safely.
Your boiler has stopped working because water is not moving through the system or a sensor is disconnected, preventing it from heating up safely.
What to check first
- Press the reset button or turn the control knob to 'R' for five seconds.
- Ensure all radiator valves are open and not stuck shut.
- Check that the boiler pressure is within the green zone (typically 1.0 to 1.5 bar).
Parts commonly replaced
- Circulation pump
- Temperature sensor (NTC thermistor)
- Wiring harness
E.01 – .20 Your boiler has become too hot because water is not moving through the system properly or a safety sensor has detected an overheating issue.
Your boiler has become too hot because water is not moving through the system properly or a safety sensor has detected an overheating issue.
What to check first
- Check that your home's radiator valves are fully open to allow water flow.
- Ensure your boiler pressure is between 1.0 and 1.5 bar on the pressure gauge.
- Try resetting the boiler to see if the fault clears.
Parts commonly replaced
- Circulation pump
- Flue gas NTC sensor
- Main Heat Exchanger (cleaning or replacement)
E.02 – .00 Your boiler is simply acknowledging that the reset button was pressed or the power was cycled, and it is usually not a cause for concern.
Your boiler is simply acknowledging that the reset button was pressed or the power was cycled, and it is usually not a cause for concern.
What to check first
- Check if the boiler resumes normal operation after the reset sequence finishes
- Ensure there is a demand for heating or hot water
- Monitor the display to see if a more specific error code appears
E.02 – .07 Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
What to check first
- Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.
- Slowly open the one or two valves on the hose until you hear water flowing.
- Watch the pressure gauge and close the valves tightly once the needle reaches between 1.0 and 1.5 bar.
Parts commonly replaced
- Filling loop
- Expansion vessel
- Pressure relief valve
E.02 – .16 Your boiler's internal computer has suffered a critical failure or a communication timeout, meaning it can no longer safely control the heating process.
Your boiler's internal computer has suffered a critical failure or a communication timeout, meaning it can no longer safely control the heating process.
Parts commonly replaced
- Main Printed Circuit Board (PCB)
- Channel Service Unit
E.02 – .17 Your boiler's computer cannot talk to the internal part that controls the gas flow, meaning the system has shut down for safety.
Your boiler's computer cannot talk to the internal part that controls the gas flow, meaning the system has shut down for safety.
Parts commonly replaced
- Gas Valve
- Printed Circuit Board (PCB)
- Wiring Harness
Related codes
E.02 – .19 Your boiler's electronic control board has detected an incorrect internal setting which is preventing it from running correctly.
Your boiler's electronic control board has detected an incorrect internal setting which is preventing it from running correctly.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Selector Jumper
E.02 – .20 Your boiler’s internal control board has detected an incorrect configuration setting which is preventing it from starting up correctly.
Your boiler’s internal control board has detected an incorrect configuration setting which is preventing it from starting up correctly.
Parts commonly replaced
- Main Printed Circuit Board (PCB)
- Jumper Link
Showing 51–60 of 129
E.02 – .21 Your boiler's internal computer settings have been changed or detected a configuration error, meaning the control board doesn't know which model it is supposed to be operating.
Your boiler's internal computer settings have been changed or detected a configuration error, meaning the control board doesn't know which model it is supposed to be operating.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Jumper Link
E.02 – .47 Your boiler is having trouble talking to your external thermostat or heating controls due to a wiring issue.
Your boiler is having trouble talking to your external thermostat or heating controls due to a wiring issue.
Parts commonly replaced
- External Programmer
- Wiring Harness
- RF Receiver
E.02 – .48 Your boiler is struggling to talk to your wireless thermostat or smart home controller, meaning they aren't working together to turn your heating on.
Your boiler is struggling to talk to your wireless thermostat or smart home controller, meaning they aren't working together to turn your heating on.
What to check first
- Check if your wireless thermostat has run out of batteries and replace them if necessary.
- Ensure the internet bridge or receiver is plugged in and has power.
- Try resetting the connection between the boiler receiver and the thermostat following the manufacturer's manual.
Parts commonly replaced
- Wireless thermostat batteries
- RF Receiver unit
- Smart room thermostat
E.04 – .00 Your boiler's internal computer cannot communicate with the part that controls the gas supply, meaning it cannot ignite to provide heat or hot water.
Your boiler's internal computer cannot communicate with the part that controls the gas supply, meaning it cannot ignite to provide heat or hot water.
Parts commonly replaced
- Gas Valve
- Printed Circuit Board (PCB)
- Wiring Harness
E.04 – .01 Your boiler has stopped working because it cannot correctly measure the temperature of the water leaving the unit due to a faulty or disconnected sensor.
Your boiler has stopped working because it cannot correctly measure the temperature of the water leaving the unit due to a faulty or disconnected sensor.
Parts commonly replaced
- Flow Temperature Sensor (NTC Thermistor)
- Wiring Harness
E.04 – .02 Your boiler has stopped working because it can no longer accurately measure the temperature of the water leaving the unit.
Your boiler has stopped working because it can no longer accurately measure the temperature of the water leaving the unit.
Parts commonly replaced
- Flow Temperature Sensor (NTC Thermistor)
- Wiring Harness
E.04 – .03 Your boiler has shut down because the water inside is getting too hot too quickly, usually because it isn't moving through the system properly.
Your boiler has shut down because the water inside is getting too hot too quickly, usually because it isn't moving through the system properly.
What to check first
- Check that your system pressure is between 1.0 and 1.5 bar on the gauge
- Ensure all radiator valves and any isolation valves under the boiler are fully open
- Bleed your radiators to remove any trapped air that might be blocking water flow
Parts commonly replaced
- Central heating pump
- Flow temperature sensor (NTC)
- Main heat exchanger (flushing/cleaning)
E.04 – .04 Your boiler has detected a problem with the sensor that monitors exhaust gases, and it has shut down for safety purposes.
Your boiler has detected a problem with the sensor that monitors exhaust gases, and it has shut down for safety purposes.
Parts commonly replaced
- Flue Temperature Sensor (NTC)
- Wiring harness
- Main PCB
E.04 – .05 Your boiler has detected a problem with the sensor that monitors the temperature of the exhaust gases, meaning it has shut down for safety.
Your boiler has detected a problem with the sensor that monitors the temperature of the exhaust gases, meaning it has shut down for safety.
Parts commonly replaced
- Flue Overheat Thermostat
- Flue NTC Sensor
- Wiring Harness
E.04 – .06 Your boiler has shut down because it is getting too hot inside, most likely because water isn't moving through the system properly or a safety sensor is broken.
Your boiler has shut down because it is getting too hot inside, most likely because water isn't moving through the system properly or a safety sensor is broken.
Parts commonly replaced
- Circulation Pump
- Heat Exchanger
- Flue Gas Sensor
- Main PCB
Showing 61–70 of 129
E.04 – .08 Your boiler has reached an unsafe temperature and has locked itself out to prevent damage or overheating.
Your boiler has reached an unsafe temperature and has locked itself out to prevent damage or overheating.
What to check first
- Check that all radiator valves are fully open
- Ensure the system pressure is between 1.0 and 1.5 bar
- Try to reset the boiler if it has cooled down for 30 minutes
Parts commonly replaced
- Overheat Thermostat
- Circulation Pump
- Temperature NTC Sensor
E.04 – .10 Your boiler is trying to start up but cannot successfully light the gas flame to provide heat or hot water.
Your boiler is trying to start up but cannot successfully light the gas flame to provide heat or hot water.
What to check first
- Check if other gas appliances, like a hob, are working to confirm your gas supply is active
- Ensure your gas meter has credit if you use a pre-payment meter
- Reset the boiler by following the instructions in your user manual
Parts commonly replaced
- Ignition Electrode
- Gas Valve
- Flame Sensing Probe
E.04 – .12 Your boiler thinks a flame is burning when it shouldn't be, which is a safety conflict that prevents the system from starting.
Your boiler thinks a flame is burning when it shouldn't be, which is a safety conflict that prevents the system from starting.
Parts commonly replaced
- Ionisation Probe
- Gas Valve
- Printed Circuit Board (PCB)
E.04 – .13 Your boiler has stopped working because the internal fan, which safely pushes exhaust gases out of the flue, is either stuck or not communicating with the system.
Your boiler has stopped working because the internal fan, which safely pushes exhaust gases out of the flue, is either stuck or not communicating with the system.
Parts commonly replaced
- Fan assembly
- Fan wiring harness
- Printed Circuit Board (PCB)
E.04 – .17 Your boiler has detected a serious issue with the gas flow or the unit that mixes gas and air, preventing it from firing up safely.
Your boiler has detected a serious issue with the gas flow or the unit that mixes gas and air, preventing it from firing up safely.
Parts commonly replaced
- Gas valve
- Gas/air unit (venturi)
- Printed Circuit Board (PCB)
E0 Your boiler's internal thermometer is likely broken or disconnected, meaning the system doesn't know how hot the water is and has shut down as a safety precaution.
Your boiler's internal thermometer is likely broken or disconnected, meaning the system doesn't know how hot the water is and has shut down as a safety precaution.
Parts commonly replaced
- NTC Temperature Sensor
- Wiring Harness
Related codes
E1 Your boiler has got too hot and has shut itself down as a safety precaution to prevent damage.
Your boiler has got too hot and has shut itself down as a safety precaution to prevent damage.
What to check first
- Switch off the boiler and allow it to cool down completely.
- Use a radiator key to bleed air from all your radiators, starting with the ones on the ground floor.
- Check your system pressure gauge and top it up if it has dropped below 1.0 bar.
- Press the reset button on the boiler to see if it restarts.
Parts commonly replaced
- Overheat Thermostat
- Circulation Pump
- Thermistor (NTC Sensor)
Related codes
E2 Your boiler is struggling to push water around the system, which is usually caused by trapped air or a blockage.
Your boiler is struggling to push water around the system, which is usually caused by trapped air or a blockage.
What to check first
- Turn off the boiler and wait for the radiators to cool down.
- Use a radiator key to bleed any trapped air from all radiators.
- Check the boiler pressure gauge and top it up to 1.5 bar if it has dropped.
Parts commonly replaced
- Circulation Pump
- Pump Overrun Thermostat
- Flow/Return Thermistor
Related codes
E3 Your boiler's internal computer has developed a fault and is unable to control the system safely.
Your boiler's internal computer has developed a fault and is unable to control the system safely.
Parts commonly replaced
- Main Printed Circuit Board
- Wiring Harness
Related codes
E4 Your boiler has failed to light, which may be caused by trapped air in your heating system preventing proper operation.
Your boiler has failed to light, which may be caused by trapped air in your heating system preventing proper operation.
What to check first
- Switch off the boiler and wait for the system to cool down
- Identify which radiators have cold spots at the top
- Use a radiator key to bleed air from those radiators until water appears
- Check your boiler pressure gauge and top up to 1.5 bar if required
- Attempt to reset the boiler
Parts commonly replaced
- Ignition electrode
- Gas valve
- Flame sensing cable
Related codes
Showing 71–80 of 129
E09 Your boiler has lost communication with the gas valve, meaning it cannot ignite to provide heating or hot water.
Your boiler has lost communication with the gas valve, meaning it cannot ignite to provide heating or hot water.
Parts commonly replaced
- Gas valve wiring harness
- Gas control valve
- Printed Circuit Board (PCB)
Related codes
E10 Your boiler is struggling to work out how hard it needs to fire because its external thermometer has stopped communicating correctly.
Your boiler is struggling to work out how hard it needs to fire because its external thermometer has stopped communicating correctly.
Parts commonly replaced
- Outdoor weather compensation sensor
- Sensor wiring harness
Related codes
E12 Your boiler has detected that water is not circulating correctly through the system, which is preventing it from firing up for your heating or hot water.
Your boiler has detected that water is not circulating correctly through the system, which is preventing it from firing up for your heating or hot water.
What to check first
- Check that your system pressure is between 1.0 and 1.5 bar
- Ensure all radiator valves and isolation valves under the boiler are fully open
- Bleed your radiators to remove any trapped air that might be blocking water flow
Parts commonly replaced
- Differential pressure switch
- Central heating pump
- Flow pipe thermistor
Related codes
E13 Your boiler has detected that a internal water sensor is stuck in the 'on' position, preventing the system from starting its safety checks.
Your boiler has detected that a internal water sensor is stuck in the 'on' position, preventing the system from starting its safety checks.
Parts commonly replaced
- Differential pressure switch
- Microswitch
- Circulation pump
Related codes
E15 Your boiler's internal computer is having trouble communicating with the gas valve, preventing the system from ignition.
Your boiler's internal computer is having trouble communicating with the gas valve, preventing the system from ignition.
Parts commonly replaced
- Gas Valve
- Printed Circuit Board (PCB)
- Wiring Harness
Related codes
E20 Your boiler's temperature sensor has developed a fault, meaning the system can no longer tell how hot the water is and has shut down as a precaution.
Your boiler's temperature sensor has developed a fault, meaning the system can no longer tell how hot the water is and has shut down as a precaution.
Parts commonly replaced
- Central Heating NTC Thermistor
- Wiring Harness
Related codes
E28 Your boiler has detected a problem with how it disposes of waste gases or a sensor error, causing it to shut down for safety.
Your boiler has detected a problem with how it disposes of waste gases or a sensor error, causing it to shut down for safety.
Parts commonly replaced
- Flue NTC Sensor
- Air Pressure Switch
- Condensate Trap
Related codes
E40 Your boiler has detected an issue with the sensor that monitors the temperature of the water coming back from your radiators, preventing the system from operating correctly.
Your boiler has detected an issue with the sensor that monitors the temperature of the water coming back from your radiators, preventing the system from operating correctly.
Parts commonly replaced
- Return NTC thermistor
- Wiring harness
- Main PCB
Related codes
E50 Your boiler is struggling to accurately measure the temperature of your hot water, which usually means it can't heat your water correctly or safely.
Your boiler is struggling to accurately measure the temperature of your hot water, which usually means it can't heat your water correctly or safely.
Parts commonly replaced
- Hot water NTC thermistor
- Wiring harness
- Control board
Related codes
E53 Your boiler is struggling to breathe properly because it cannot safely exhaust its fumes, causing it to shut down for your safety.
Your boiler is struggling to breathe properly because it cannot safely exhaust its fumes, causing it to shut down for your safety.
Parts commonly replaced
- Flue ducting
- Gas valve
- Fan assembly
Related codes
Showing 81–90 of 129
E54 Your boiler is struggling to detect when you turn on a hot tap, meaning you might have inconsistent or no hot water.
Your boiler is struggling to detect when you turn on a hot tap, meaning you might have inconsistent or no hot water.
Parts commonly replaced
- DHW Flow Sensor
- Flow Turbine
- Wiring Harness
Related codes
E55 Your boiler has lost its fine-tuning and needs to re-learn how to burn gas efficiently and safely.
Your boiler has lost its fine-tuning and needs to re-learn how to burn gas efficiently and safely.
Parts commonly replaced
- Gas Valve
- Printed Circuit Board (PCB)
- Ionisation Electrode
Related codes
E78 Your boiler is struggling to accurately monitor its own water pressure, which means it cannot tell if it is safe to operate.
Your boiler is struggling to accurately monitor its own water pressure, which means it cannot tell if it is safe to operate.
Parts commonly replaced
- Water pressure sensor
- Sensor wiring harness
- PCB
Related codes
E83/E84/E85/E86/E87 Your boiler's main control board has lost connection with its internal electronic components, meaning it cannot send or receive instructions to operate.
Your boiler's main control board has lost connection with its internal electronic components, meaning it cannot send or receive instructions to operate.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Wiring Harness
- User Interface Panel
E92 Your boiler has detected an issue with the air and gas mix while trying to automatically tune itself for safe operation.
Your boiler has detected an issue with the air and gas mix while trying to automatically tune itself for safe operation.
Parts commonly replaced
- Gas valve
- Electrode set
- PCB
Related codes
E100 Your boiler’s internal computer has lost track of the time or date, which is preventing its scheduled heating cycles from starting correctly.
Your boiler’s internal computer has lost track of the time or date, which is preventing its scheduled heating cycles from starting correctly.
What to check first
- Locate the control panel on the front of the boiler
- Navigate to the settings menu using the buttons provided
- Manually reset the current time and date to clear the error
Parts commonly replaced
- Printed Circuit Board (PCB)
- Display Interface
E109 Your boiler is struggling to move water through the system efficiently, which is causing it to shut down to prevent overheating.
Your boiler is struggling to move water through the system efficiently, which is causing it to shut down to prevent overheating.
What to check first
- Check that the boiler pressure is between 1.0 and 1.5 bar
- Ensure all radiator valves and internal stop taps are fully open
- Bleed all radiators to remove trapped air that might be blocking water flow
Parts commonly replaced
- Circulation pump
- Flow temperature sensor
- Main heat exchanger (de-scaling)
Related codes
E110 Your boiler has shut down because it has detected it is getting too hot, usually due to a lack of water flow or a circulation problem.
Your boiler has shut down because it has detected it is getting too hot, usually due to a lack of water flow or a circulation problem.
What to check first
- Check that your system pressure is between 1.0 and 1.5 bar on the gauge
- Ensure all radiator valves and isolation valves under the boiler are fully open
- Try resetting the boiler by turning the selector switch to 'R' for five seconds
Parts commonly replaced
- Overheat Thermostat
- Circulating Pump
- Temperature Sensors (NTC)
Related codes
E117 Your boiler has detected that there is too much water pressure in the system, which can prevent it from running safely.
Your boiler has detected that there is too much water pressure in the system, which can prevent it from running safely.
What to check first
- Locate a radiator bleed valve and a radiator key
- Slowly open the valve to release a small amount of water into a container
- Monitor the boiler pressure gauge until it falls back into the green zone (typically 1.0 to 1.5 bar)
Parts commonly replaced
- Expansion Vessel
- Filling Loop Tap
- Pressure Relief Valve
Related codes
E118 Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
What to check first
- Locate the filling loop (usually a silver braided hose with small valves) underneath or near the boiler.
- Slowly open the valve(s) to allow fresh water into the system while watching the pressure gauge.
- Close the valves tightly once the pressure gauge reaches between 1.0 and 1.5 bar.
Parts commonly replaced
- Filling loop
- Expansion vessel
- Pressure sensor
Related codes
Showing 91–100 of 129
E119 Your boiler has stopped working because the water pressure is too low for it to run safely.
Your boiler has stopped working because the water pressure is too low for it to run safely.
What to check first
- Check the pressure gauge on the front of the boiler or under the casing
- Locate the filling loop (a flexible silver hose with small lever valves)
- Slowly open the valves to top up the water until the gauge reads between 1.0 and 1.5 bar
- Close the valves tightly and restart the boiler
Parts commonly replaced
- External filling loop
- Water pressure switch
- Expansion vessel
Related codes
E125 Your boiler is struggling to move water around the system correctly, which is likely causing it to overheat and shut down for safety.
Your boiler is struggling to move water around the system correctly, which is likely causing it to overheat and shut down for safety.
Parts commonly replaced
- Circulation pump
- Plate heat exchanger
- Diverter valve
Related codes
E128 Your boiler is struggling to keep its burner lit and has automatically shut down for safety after failing to maintain a flame multiple times.
Your boiler is struggling to keep its burner lit and has automatically shut down for safety after failing to maintain a flame multiple times.
Parts commonly replaced
- Ionisation probe
- Flame sensing electrode
- Gas valve
- PCB (Printed Circuit Board)
Related codes
E129 Your boiler is struggling to keep a steady flame while it tries to set itself up, causing it to shut down for safety.
Your boiler is struggling to keep a steady flame while it tries to set itself up, causing it to shut down for safety.
Parts commonly replaced
- Flame sensing electrode
- Ignition lead
- Gas valve
Related codes
E130 Your boiler has sensed that the exhaust gases are getting too hot and has shut down as a safety precaution.
Your boiler has sensed that the exhaust gases are getting too hot and has shut down as a safety precaution.
Parts commonly replaced
- Flue NTC Sensor
- Main Heat Exchanger (cleaning or replacement)
- Wiring Harness
Related codes
E131 Your boiler has sensed that the exhaust gases are becoming dangerously hot and has shut itself down as a safety precaution.
Your boiler has sensed that the exhaust gases are becoming dangerously hot and has shut itself down as a safety precaution.
Parts commonly replaced
- Heat exchanger
- Flue thermistor
- Flue sensor
- Main PCB
Related codes
E133 Your boiler has failed to light because it either isn't receiving gas or is unable to detect a flame.
Your boiler has failed to light because it either isn't receiving gas or is unable to detect a flame.
What to check first
- Check if other gas appliances, like a hob, are working to confirm your gas supply is on
- Check if your gas meter has credit (if using a pre-payment meter)
- Check if the condensate pipe (the white plastic pipe outside) is frozen and defrost it with warm water
- Press and hold the reset button for five seconds
Parts commonly replaced
- Ignition electrode
- Gas valve
- PCB (Circuit board)
Related codes
E134 Your boiler has failed to light several times in a row, often because the gas supply is interrupted or the ignition system cannot detect a flame.
Your boiler has failed to light several times in a row, often because the gas supply is interrupted or the ignition system cannot detect a flame.
Parts commonly replaced
- Gas valve
- Ignition electrode
- Flame sensing probe
- PCB
Related codes
E135 Your boiler has stopped working because it cannot detect a steady flow of gas, which is likely caused by an internal component failure or an issue with your gas supply.
Your boiler has stopped working because it cannot detect a steady flow of gas, which is likely caused by an internal component failure or an issue with your gas supply.
Parts commonly replaced
- Gas Valve
- Printed Circuit Board (PCB)
- Ignition Electrode
Related codes
E154 Your boiler has detected that the water temperature sensors are giving conflicting readings, suggesting water isn't moving through the system correctly.
Your boiler has detected that the water temperature sensors are giving conflicting readings, suggesting water isn't moving through the system correctly.
Parts commonly replaced
- Flow temperature sensor
- Return temperature sensor
- Circulation pump
Related codes
Showing 101–110 of 129
E160 Your boiler has stopped working because the fan that clears away waste gases is not spinning or communicating correctly with the main control board.
Your boiler has stopped working because the fan that clears away waste gases is not spinning or communicating correctly with the main control board.
Parts commonly replaced
- Fan assembly
- Printed Circuit Board (PCB)
- Wiring harness
Related codes
E160 / E161 Your boiler has detected a problem with the fan that clears away waste gases, which means it cannot fire up safely for heating or hot water.
Your boiler has detected a problem with the fan that clears away waste gases, which means it cannot fire up safely for heating or hot water.
Parts commonly replaced
- Fan assembly
- Printed Circuit Board (PCB)
- Wiring harness
Related codes
E163 Your boiler's hot water sensor has failed or has a wiring issue, meaning it cannot accurately measure or provide hot water.
Your boiler's hot water sensor has failed or has a wiring issue, meaning it cannot accurately measure or provide hot water.
Parts commonly replaced
- DHW NTC thermistor sensor
- Wiring harness
- Main PCB
Related codes
E164 Your boiler has lost track of the water pressure level inside the system, preventing it from heating up or providing hot water.
Your boiler has lost track of the water pressure level inside the system, preventing it from heating up or providing hot water.
Parts commonly replaced
- Water Pressure Sensor
- Wiring Harness
- Main PCB
Related codes
E167 Your boiler's internal computer has encountered a communication glitch or a hardware failure and is unable to control the heating process.
Your boiler's internal computer has encountered a communication glitch or a hardware failure and is unable to control the heating process.
Parts commonly replaced
- Main Printed Circuit Board (PCB)
- Electrical wiring harness
Related codes
E168 Your boiler has experienced a memory error and has shut down because its internal computer can no longer confirm it is operating safely.
Your boiler has experienced a memory error and has shut down because its internal computer can no longer confirm it is operating safely.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Wiring Harness
Related codes
E193 Your boiler has detected that water is not circulating properly before the burner starts up, often caused by an air lock or a blockage in the system.
Your boiler has detected that water is not circulating properly before the burner starts up, often caused by an air lock or a blockage in the system.
What to check first
- Check that your system pressure is between 1.0 and 1.5 bar
- Ensure all radiator valves and isolation valves are fully open
- Gently bleed your radiators to remove any trapped air
Parts commonly replaced
- Circulation Pump
- Automatic Air Vent
- Flow Temperature Sensor
Related codes
E270 Your boiler is overheating because water isn't moving through the system properly, which has caused it to shut down to prevent damage.
Your boiler is overheating because water isn't moving through the system properly, which has caused it to shut down to prevent damage.
What to check first
- Check that your system pressure is between 1 and 1.5 bar
- Ensure all radiator valves and the boiler isolation valves are fully open
- Try bleeding your radiators to remove any trapped air pockets
- Reset the boiler once the system has cooled down
Parts commonly replaced
- Central heating pump
- Main heat exchanger
- Flow and return thermistors
Related codes
E317 Your boiler has detected that the electricity coming into your home is at the wrong frequency, which is preventing it from running safely.
Your boiler has detected that the electricity coming into your home is at the wrong frequency, which is preventing it from running safely.
Parts commonly replaced
- Main PCB
- Internal wiring harness
Related codes
E321 Your boiler's hot water sensor has detected an electrical fault or an unusual temperature reading, meaning your taps may not get as hot as they should.
Your boiler's hot water sensor has detected an electrical fault or an unusual temperature reading, meaning your taps may not get as hot as they should.
Parts commonly replaced
- DHW NTC thermistor
- Wiring harness
Related codes
Showing 111–120 of 129
E384 Your boiler thinks it sees a flame even though it hasn't finished its startup checks, so it has shut down for safety.
Your boiler thinks it sees a flame even though it hasn't finished its startup checks, so it has shut down for safety.
Parts commonly replaced
- Flame Sensing Electrode
- Gas Valve
- Printed Circuit Board (PCB)
Related codes
E385 Your boiler is not receiving enough electrical power from the main supply to operate safely and has shut down as a result.
Your boiler is not receiving enough electrical power from the main supply to operate safely and has shut down as a result.
What to check first
- Check if there is a partial power cut or 'brownout' in your local area
- Ensure your fuse box / consumer unit hasn't tripped a circuit
- Switch the boiler off at the fused spur switch, wait 30 seconds, and switch it back on to reset it
Parts commonly replaced
- Printed Circuit Board (PCB)
- External Voltage Stabiliser
- Electrical Fused Spur
Related codes
E430 Your boiler has detected a sudden drop in water pressure and is pausing to check if the system can maintain the correct levels.
Your boiler has detected a sudden drop in water pressure and is pausing to check if the system can maintain the correct levels.
What to check first
- Check the pressure gauge on your boiler or piping; it should be between 1.0 and 1.5 bar.
- If it is too low, use the filling loop valves to top up the water pressure.
- Ensure all radiator bleed valves are tightly closed and check for any visible leaks around the system.
Parts commonly replaced
- Filling loop
- Expansion vessel
- Water pressure sensor
Related codes
H.01 – .00 Your boiler has stopped working because the internal computer has lost contact with the control system that regulates the gas supply.
Your boiler has stopped working because the internal computer has lost contact with the control system that regulates the gas supply.
Parts commonly replaced
- Gas Valve
- Main Control Board (PCB)
- Wiring Harness
Related codes
H.01 – .05 Your boiler is overheating because water isn't moving through the system quickly enough to stay at a safe temperature.
Your boiler is overheating because water isn't moving through the system quickly enough to stay at a safe temperature.
What to check first
- Ensure all radiator valves (TRVs) are fully open
- Check that the boiler pressure is between 1 and 1.5 bar on the gauge
- Bleed all radiators to remove trapped air pockets
Parts commonly replaced
- Central heating pump
- Flow/Return thermistors (NTC sensors)
- Main heat exchanger (flushing)
Related codes
H.01 – .08 Your boiler is overheating or struggling to move water through the system correctly, causing it to shut down for safety.
Your boiler is overheating or struggling to move water through the system correctly, causing it to shut down for safety.
What to check first
- Check that your radiator valves are open
- Ensure the system pressure is between 1 and 1.5 bar on the gauge
- Gently bleed your radiators to remove trapped air
Parts commonly replaced
- Circulation pump
- Temperature sensors (NTC thermistors)
- Main heat exchanger
Related codes
H.01 – .14 Your boiler has detected that it is getting too hot too quickly, usually because the water isn't moving through the system properly.
Your boiler has detected that it is getting too hot too quickly, usually because the water isn't moving through the system properly.
What to check first
- Check that your radiator valves are fully open to allow water to flow.
- Verify that your boiler pressure gauge is between 1 and 1.5 bar.
- Try resetting the boiler to see if the temporary fault clears.
Parts commonly replaced
- Circulation pump
- Central heating filter (cleaning)
- Flow temperature sensor
Related codes
H.01 – .18 Your boiler is struggling to move water around the system correctly, which is preventing it from heating up safely.
Your boiler is struggling to move water around the system correctly, which is preventing it from heating up safely.
What to check first
- Check that your radiator valves are fully open
- Check the boiler pressure gauge and top up to 1.5 bar if it is low
- Bleed your radiators to remove any trapped air pockets
- Reset the boiler to see if the code clears
Parts commonly replaced
- Circulation pump
- NTC thermistor (Temperature sensor)
- Main heat exchanger (Powerflush required)
Related codes
H.01 – .21 Your boiler is shutting down because it is heating up much too quickly when you turn on your taps, usually because the water isn't moving through the system properly.
Your boiler is shutting down because it is heating up much too quickly when you turn on your taps, usually because the water isn't moving through the system properly.
What to check first
- Check that the cold water mains stopcock is fully open
- Ensure all isolation valves underneath the boiler are in the open position
- Try resetting the boiler to see if the error clears
Parts commonly replaced
- DHW Temperature Sensor (NTC)
- Plate Heat Exchanger
- Circulation Pump
H.02 – .02 Your boiler's main control board has lost its internal settings and does not know which model it is currently operating.
Your boiler's main control board has lost its internal settings and does not know which model it is currently operating.
Parts commonly replaced
- Printed Circuit Board (PCB)
- PCB Configuration Plug
Showing 121–129 of 129
H.02 – .03 Your boiler's internal computer has matching or settings errors that are temporarily preventing it from starting up correctly.
Your boiler's internal computer has matching or settings errors that are temporarily preventing it from starting up correctly.
Parts commonly replaced
- Main PCB
- Parameter Key
- Display Board
H.02 – .04 Your boiler's internal computer has become confused by its settings, causing it to stop working for safety.
Your boiler's internal computer has become confused by its settings, causing it to stop working for safety.
What to check first
- Locate the reset button or selector switch on the front control panel
- Press and hold the reset button for 5 seconds, or turn the switch to 'R' and back to 'On'
- Wait for the boiler to complete its restart sequence to see if the error clears
Parts commonly replaced
- Main PCB (Printed Circuit Board)
- Parameter Key
H.02 – .06 Your boiler has detected that the water pressure is too low, likely caused by a leak or a lack of water in the system.
Your boiler has detected that the water pressure is too low, likely caused by a leak or a lack of water in the system.
What to check first
- Locate the filling loop (the flexible silver hose usually under the boiler)
- Slowly open the valves to top up the system until the pressure gauge reads between 1 and 1.5 bar
- Close both valves tightly and restart the boiler
Parts commonly replaced
- Automatic Air Vent
- Expansion Vessel
- Pressure Relief Valve
H.03 -.00 Your boiler is struggling to communicate with its internal temperature sensors, which is preventing it from heating up correctly.
Your boiler is struggling to communicate with its internal temperature sensors, which is preventing it from heating up correctly.
Parts commonly replaced
- NTC Temperature Sensor
- Flue Sensor
- Wiring Harness
Related codes
H.03 – .01 Your boiler's internal computer is having trouble talking to its main control board, preventing the system from starting up.
Your boiler's internal computer is having trouble talking to its main control board, preventing the system from starting up.
Parts commonly replaced
- Main PCB
- Wiring Harness
- Display PCB
H.03 – .02 Your boiler has lost its flame while it was running, meaning it has shut down as a safety precaution and cannot provide heat or hot water.
Your boiler has lost its flame while it was running, meaning it has shut down as a safety precaution and cannot provide heat or hot water.
Parts commonly replaced
- Flame sensing electrode
- Gas valve
- Ignition lead
- Printed Circuit Board (PCB)
Related codes
OFF OFF OFF Your boiler has no electricity and is completely powered down, which means it will not provide any heating or hot water.
Your boiler has no electricity and is completely powered down, which means it will not provide any heating or hot water.
What to check first
- Check if your home's main fuse box (consumer unit) has tripped and flip the switch back up if necessary.
- Locate the boiler's power switch (usually a fused spur on the wall near the unit) and ensure it is turned on.
- Check if other appliances are working to rule out a general power cut.
Parts commonly replaced
- Internal Glass Fuse
- Printed Circuit Board (PCB)
- Fused Connection Unit (Wall switch)
ON OFF ON Your boiler has failed to light after several attempts and has locked itself out for safety.
Your boiler has failed to light after several attempts and has locked itself out for safety.
What to check first
- Check that your gas supply is turned on at the meter
- Check if other gas appliances in your home are working
- Press the reset button once to see if the boiler restarts
Parts commonly replaced
- Ignition electrode
- Flame sensing probe
- Gas valve
ON ON ON Your boiler has detected an internal electrical communication problem that is preventing it from starting up safely.
Your boiler has detected an internal electrical communication problem that is preventing it from starting up safely.
Parts commonly replaced
- Wiring harness
- Control PCB
- Low voltage cable assembly