27 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler is currently in a manual service mode used for internal checks and is not indicating a broken part.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Your boiler has switched itself off because it started to light but the flame went out or could not be detected.
Your boiler has stopped working because the internal fan, which safely exhausts gases produced during heating, is not running correctly.
Your boiler has likely stopped heating because a sensor that measures the temperature of the water leaving the unit has failed or become disconnected.
Your boiler's internal sensor that monitors the temperature of the water coming back into the unit has developed a fault, preventing the system from operating correctly.
Your boiler is having trouble communicating with the optional sensor that measures the temperature outside, which may cause your heating to behave unpredictably.
Your boiler is not receiving enough electrical power from the grid to operate safely and has shut down as a precaution.
Your boiler's internal computer brain either hasn't been set up correctly or has developed a hardware failure, preventing the unit from starting.
Your boiler's main control board hasn't been set up correctly to tell it which model it is, so it doesn't know how to operate yet.
Your boiler has detected that the temperature sensors are reading back-to-front or are failing, causing it to shut down for safety.
Your boiler has failed to maintain a flame, which means it has stopped providing heating and hot water to protect itself.
Your boiler has detected that water is getting too hot too quickly because it isn't circulating through your radiators or pipes correctly.
Your boiler has shut down because the water inside it has become too hot, usually due to a lack of water flow or a circulation problem.
Your boiler has tried to light several times but cannot establish a flame, meaning it has shut down for safety.
Your boiler has detected a problem with the internal sensor that monitors the temperature of the water as it leaves the unit, causing the system to shut down as a safety precaution.
Your boiler has detected a problem with the sensor that monitors the temperature of the water returning to the unit, causing it to shut down for safety.
Your boiler thinks it sees a flame when there shouldn't be one, so it has shut down as a safety precaution.
Your boiler's internal computer brain either isn't set up correctly or has developed a technical hardware fault, preventing the unit from starting.
Your boiler’s main computer chip has forgotten its settings or has developed an internal electrical failure, meaning the unit cannot function.
Your boiler is repeatedly failing to start and has locked itself out for safety after five unsuccessful attempts in a short period.
Your boiler is struggling to keep its flame lit, which means it cannot heat your water or radiators.
Your boiler is currently stuck in a technical programming mode used by engineers and is not currently in its normal operating state.
Your boiler is currently in service mode, which is an intentional setting used by engineers to test the system and not a mechanical breakdown.
Your boiler is not actually broken; it is currently in a manual service mode used by engineers to test the system or displays a history of recent issues.
Your boiler is currently in a manual testing or service mode used by engineers and is not actually reporting a breakage or fault.
Your boiler is currently stuck in its internal computer programming mode and hasn't been set up to operate as a heater yet.
BoilerFaultCodes