32 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler's internal computer screen and main control board are having trouble talking to each other, meaning the unit cannot function.
Your boiler has lost its connection to the sensor that monitors the temperature of the water leaving the unit, causing it to stop running as a safety precaution.
Your boiler has stopped working because one of its internal temperature sensors has lost connection or failed.
Your boiler has stopped working because one of its internal sensors has developed an electrical fault and can no longer measure the temperature of the water leaving the unit.
Your boiler has detected an electrical fault with the sensor that monitors water returning from your radiators, causing the system to shut down for safety.
Your boiler has detected an electrical fault with the sensor that monitors your hot water tank temperature, preventing it from heating your water correctly.
Your boiler has switched itself off because it has detected that the water inside is getting too hot.
Your boiler has stopped working because the water pressure is too low for it to run safely.
Your boiler is struggling to move water around the system properly, causing it to overheat and shut down for safety.
Your boiler is heating up too quickly because water isn't flowing through the system properly, causing it to shut down to prevent overheating.
Your boiler has detected an electrical connection issue or a sudden temperature rise, causing it to shut down for safety.
Your boiler's safety system is detecting a flame when there shouldn't be one, or the sensor that monitors the flame has developed a fault.
Your boiler is not receiving gas or is unable to light a flame to provide heating and hot water.
Your boiler has lost its flame while running and is now unable to relight itself to provide heat or hot water.
Your boiler has detected an issue with the air fan, meaning it cannot safely circulate the air and gas needed to stay lit.
Your boiler has lost communication with its external controls, such as your thermostat, often due to an electrical wiring error or interference.
Your boiler has detected an electrical communication problem with the gas valve, which is preventing it from lighting safely.
Your boiler has detected a potential safety issue where the gas valve is not closing properly or the control board is misreading the gas flow.
Your boiler's internal computer brain has developed a memory error and can no longer process the information it needs to run safely.
Your boiler has detected an electrical fault or a sensor failure and has shut down as a safety precaution.
Your boiler’s internal computer has overheated, causing it to shut down to prevent permanent damage.
Your boiler's internal computer has detected an electrical fault with the flame sensor and has shut down for safety.
Your boiler's internal computer parts have lost their identity settings or been replaced incorrectly, meaning the system can no longer communicate with itself to operate.
Your boiler has detected that a temperature sensor is stuck or faulty, meaning it cannot accurately monitor the water temperature to operate safely.
Your boiler’s temperature sensors are giving conflicting readings, causing the system to shut down to prevent overheating.
Your boiler has lost the ability to monitor its own water pressure due to a sensor or wiring fault, causing the system to shut down for safety.
Your boiler is struggling to read its internal water pressure correctly because of a technical glitch in the sensor or its wiring.
Your boiler is unable to detect a change in water pressure when the pump starts up, preventing it from firing up for heating or hot water.
Your boiler has shut down because a safety sensor has detected that the main heating component is getting too hot or has a broken internal fuse.
Your boiler has shut down because it is unable to drain away the waste water it produces, or a safety sensor on the flue system has been triggered.
Your boiler is simply running a routine check on the water flow around the system to ensure everything is moving correctly.
Your boiler is pausing briefly because it has finished its heating cycle or has reached the required temperature and is now cooling down internal components.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes