46 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler has detected that harmful exhaust fumes are not escaping correctly through the chimney or flue, causing it to shut down for your safety.
Your boiler has stopped working because the water pressure is too low and needs to be topped up.
Your boiler has detected that the water pressure inside the system is too high, often caused by overfilling or a faulty valve.
Your boiler has detected a problem with the temperature sensor that manages your hot water, which usually means your taps will not get warm.
Your boiler has detected a problem with the internal temperature sensor that monitors water leaving the unit, preventing it from heating up correctly.
Your boiler is failing to light properly because it cannot detect a flame, which means you have no heating or hot water.
Your boiler has switched itself off because it has detected that it is getting too hot, likely due to a blockage, trapped air, or a faulty safety sensor.
Your boiler is struggling to detect a flame, which means it cannot stay lit to provide heating or hot water.
Your boiler has stopped working because water is not moving around the system properly, which is preventing it from heating up safely.
Your boiler has detected an issue with a secondary sensor or its internal settings, which is preventing it from running properly.
Your boiler is unable to control its flame height correctly because of a communication issue with the gas control system.
Your boiler's computer is confused about which model it is and needs its internal settings corrected to match the physical type of unit installed.
Your boiler has detected that the exhaust gases are too hot or the sensor monitoring them has failed, causing the system to shut down for safety.
Your boiler has detected a problem with the sensor that monitors exhaust gases, and it has shut down as a safety precaution.
Your boiler has stopped working because the internal computer has lost communication with the fan that clears exhaust gases.
Your boiler has detected that its two internal temperature sensors are giving very different readings, causing it to shut down for safety.
Your boiler has stopped working because the waste water pipe is backed up or frozen, preventing the system from draining safely.
Your boiler has been manually reset too many times in a short period and has temporarily locked itself for safety reasons.
Your boiler has detected an issue with the sensor that monitors water coming back into the system, causing the unit to stop working for safety.
Your boiler has stopped working because the electrical power coming into your home from the national grid has dropped to a level that is too low for the boiler to operate safely.
Your boiler has detected an issue with the electrical power coming into your home and has shut down as a safety precaution.
Your boiler has tried and failed to light its flame several times in a row, causing it to shut down for safety.
Your boiler has detected that one of its control buttons is stuck or damaged, or there is an internal communication error on the main circuit board.
Your boiler is having trouble communicating with your smart thermostat or remote control system due to a wiring or connection issue.
Your boiler is failing to light properly because a internal safety component or the gas valve is not communicating correctly with the control board.
Your boiler has shut down because the temperature difference between the water going out and the water coming back is too wide, suggesting a circulation problem.
Your boiler has detected an inconsistency with its internal temperature readings and needs to perform a self-check to ensure it is operating correctly.
Your boiler has detected that a temperature sensor is not sitting correctly on the pipe or is giving an unusual reading, preventing it from heating your water safely.
Your boiler has detected a problem with a temperature sensor that monitors the heat of the water being sent to your taps or radiators.
Your boiler has detected an electrical issue with the gas control system, preventing it from safely lighting the burner.
Your boiler has detected an electrical fault with the gas control valve, meaning it cannot safely regulate the fuel supply to stay lit.
Your boiler has detected an internal electrical problem with the gas control valve, preventing it from lighting safely.
Your boiler has detected an internal communication failure between the control board and the gas valve, meaning it cannot safely manage the flow of gas to create heat.
Your boiler has detected a problem with how it is burning gas during start-up, often caused by a blocked vent or a sensor issue, and has locked itself for safety.
Your boiler has stopped working because it has failed to light several times in a row, often caused by a problem with the burner or the air supply.
Your boiler is struggling to burn gas correctly, which is often caused by a temporary interruption in the fuel supply or an issue with the ventilation system.
Your boiler is struggling to operate because the incoming gas supply from the street or meter is not strong enough to meet the demand.
Your boiler's internal computer has detected a serious hardware failure and has shut itself down to protect its electrical components.
Your boiler is struggling to maintain a steady flame and has shut down as a safety precaution.
Your boiler is struggling to burn gas correctly and has shut down for safety because it cannot reach its required operating settings.
Your boiler is struggling to get the correct balance of air and gas for the burner to work safely.
Your boiler is struggling to burn gas correctly and efficiently, meaning it cannot maintain the flame needed to heat your home.
Your boiler is struggling to keep a steady flame alight, causing it to cut out intermittently for safety.
Your boiler has shut down because it cannot safely expel exhaust fumes out through the external flue pipe.
Your boiler has encountered a technical software error while trying to start up and cannot function correctly.
Your boiler's main control board has suffered a critical internal failure and can no longer manage the system's functions.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes