42 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Tap any card for details
Your boiler has stopped because it cannot detect a steady flame, meaning it is temporarily shutting down for your safety.
Your boiler has detected that the water pressure inside the system is dangerously high, which can put stress on the pipes and components.
Your boiler has stopped working because the water pressure inside the system has dropped too low.
Your boiler is reminding you that it is time for its routine annual service to keep it running safely and efficiently.
Your boiler has failed to light because it isn't detecting a gas supply or a flame, leaving you without heating and hot water.
Your boiler thinks it sees a flame even though it hasn't turned the gas on yet, causing it to shut down for safety.
Your boiler has shut down because the internal water temperature has become too hot.
Your boiler has shut down because its internal temperature sensors are giving conflicting readings and can no longer monitor the heat safely.
Your boiler has stopped working because it cannot detect the temperature of the water flowing into your heating system.
Your boiler has shut down because it cannot detect any water temperature information coming back from your heating system pipes.
Your boiler has shut down because it detected a sudden, abnormal spike in temperature that could lead to overheating.
Your boiler has stopped working because the sensor that monitors the temperature of the water returning to the unit is no longer communicating correctly.
Your boiler has stopped working because it cannot correctly measure the temperature of the water leaving the unit.
Your boiler has detected a recurring drop in water pressure which suggests there is a leak somewhere in your heating system or within the boiler itself.
Your boiler has stopped working because the gas valve is not communicating correctly with the control system.
Your boiler has experienced an internal electronics failure that has caused it to shut down for safety.
Your boiler's internal computer has encountered a critical electronic failure that it cannot automatically resolve.
Your boiler has shut down because it thinks the water returning to the unit is hotter than the water leaving it, which usually indicates a circulation problem or a faulty sensor.
Your boiler is repeatedly losing its flame and has locked itself out for safety.
Your boiler has shut down because the exhaust gases are getting too hot, indicating a potential blockage or buildup in the main heat exchanger.
Your boiler has detected an internal computer error that has caused it to stop working and lock itself for safety.
Your boiler has experienced an internal electronics failure that is preventing it from starting up correctly.
Your boiler has stopped working because the fan that helps remove waste gases is not spinning correctly or communicating with the system.
Your boiler has shut down because the exhaust gases have become too hot, which is a safety measure to prevent damage to the internal components.
Your boiler has stopped working because water isn't flowing through the system properly, often caused by a blockage or a faulty pump.
Your boiler has locked itself out because the reset button has been pressed too many times in a short period.
Your boiler has detected that the electricity supply coming into your home is too weak for it to operate safely, causing the system to shut down.
Your boiler has detected an issue with the stability or frequency of your home's electrical supply, causing it to shut down for safety.
Your boiler has stopped working because the water pressure is too low for the system to run safely.
Your boiler is having trouble communicating with the sensors that monitor the temperature outside, which can prevent it from heating your home efficiently.
Your boiler has shut down because there is too much water pressure in the system, which could lead to leaks if not addressed.
Your boiler is continuously trying to fill itself with water automatically, which can indicate a system leak or a sensor fault.
Your boiler is unable to top itself up with water because the filling process has timed out, likely due to low mains pressure or a part becoming stuck.
Your boiler has tried to top itself up with water automatically but failed, meaning there isn't enough pressure for the system to run.
Your boiler has stopped working because it cannot detect a connection to the sensor that monitors water pressure.
Your boiler is having trouble 'talking' to your thermostat, which means it doesn't know when to turn your heating on or off.
Your boiler has lost communication with the temperature sensor in your hot water storage tank, meaning it cannot safely heat your water.
Your boiler has detected a problem with the sensor monitoring your solar heating system, which is causing the unit to stop operating.
Your boiler has detected a problem with the sensor that monitors your hot water temperature, which is stopping your hot water from working correctly.
Your boiler has detected a problem with the sensor that monitors exhaust gas temperatures, causing it to shut down for safety.
Your boiler has detected that its internal temperature sensors are giving conflicting readings and has shut down to prevent overheating.
Your boiler's internal computer brain is unable to talk to the display screen, meaning the system has stopped working to protect itself.
Monthly cover means no unexpected bills when your boiler breaks down.
Affiliate links. We may earn a commission at no extra cost to you.
BoilerFaultCodes