46 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler has shut down because it detected that exhaust gases have reached an unsafe temperature or are not venting correctly.
Your boiler has stopped working because the water pressure inside the system has dropped too low and needs topping up.
Your boiler has detected that the water pressure is too high, which can cause the system to stop working to protect itself.
Your boiler is having trouble measuring the temperature of your hot water, which usually means your taps will only run cold.
Your boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, meaning it cannot safely regulate heat.
Your boiler is failing to light properly, which means it cannot heat your water or radiators until the gas ignition issue is resolved.
Your boiler has overheated because the internal temperature has become too high, causing it to shut down for safety.
Your boiler is struggling to detect a flame, which prevents it from firing up to provide heating or hot water.
Your boiler is overheating because water isn't moving through the system properly.
Your boiler has detected an issue with an internal backup sensor or a settings mismatch, which is preventing it from running correctly.
Your boiler has detected a communication problem with the part that controls the gas flow, meaning it cannot ignite safely to provide heating or hot water.
Your boiler's internal computer is confused about how it should be breathing, leading to a safety lockout that prevents it from firing up.
Your boiler has detected that the exhaust gases are too hot or the temperature sensor itself has failed, causing the system to shut down for safety.
Your boiler has detected a problem with the sensor that monitors exhaust fumes, causing the system to shut down for safety.
Your boiler has detected a communication problem with the fan, which means it cannot safely move air and exhaust gases through the system.
Your boiler has detected that its internal temperature sensors are giving conflicting readings, which stops it from running as a safety precaution.
Your boiler has stopped working because waste water is backing up inside its drainage pipe, often due to a simple blockage or freezing.
Your boiler has been manually reset too many times in a short period and has temporarily locked itself for safety.
Your boiler has stopped working because a sensor that monitors the temperature of the water returning to the unit has failed.
Your boiler has shut down because the electrical power supply from the grid has dropped to a level that is too low for the unit to operate safely.
Your boiler has detected an issue with the electrical power entering your home, meaning the current is not at the steady frequency required for the unit to run safely.
Your boiler has failed to keep its flame lit several times in a row and has locked itself out for safety.
Your boiler's control panel has detected that one of the buttons is stuck or faulty, which is preventing the system from operating correctly.
Your boiler has lost its connection to the external heating controls, meaning it cannot receive instructions on when to turn the heating on.
Your boiler has failed to ignite and cannot detect a flame, which means your heating and hot water will not work until a faulty internal component is replaced.
Your boiler has shut down because the temperature difference between the water going out and the water coming back is too high, suggesting the water isn't circulating properly.
Your boiler has detected an inconsistency with its temperature sensors and has locked itself as a safety precaution until it can be recalibrated.
Your boiler has detected that a temperature sensor is not sitting correctly on its pipe, preventing it from measuring heat accurately.
Your boiler has detected an issue with a backup temperature sensor which is preventing it from monitoring heat levels safely.
Your boiler has detected an electrical fault with the gas valve control system, which means it cannot safely manage the fuel flow to stay alight.
Your boiler has detected an internal electrical fault with the gas control system, meaning it cannot safely manage the fuel flow and has shut down as a precaution.
Your boiler has detected an internal electrical fault with the gas control valve, meaning it cannot safely manage the fuel supply and has shut down.
Your boiler has detected an electrical communication problem with the internal gas valve system, meaning it cannot safely control the fuel needed for heating and hot water.
Your boiler has detected an issue with the air or gas mixture during ignition, causing it to shut down for safety.
Your boiler has stopped working because it has repeatedly failed to light correctly and has shut down for safety.
Your boiler is struggling to burn gas correctly, which is likely caused by air in the pipes or a dirty internal sensor.
Your boiler is not receiving enough gas from the mains supply to operate correctly, causing it to shut down for safety.
Your boiler’s internal computer chip has identified a critical electronic failure and has shut down to protect itself.
Your boiler is struggling to maintain a steady flame and has shut down as a safety precaution.
Your boiler is struggling to achieve the correct flame for safe combustion, causing it to shut down to prevent damage.
Your boiler is struggling to get the correct balance of air and gas for the flame and has shut down as a safety precaution.
Your boiler is struggling to control its burner flame and cannot reach the necessary power levels to heat your water or home safely.
Your boiler is struggling to maintain a steady flame, causing it to shut down for safety.
Your boiler has shut down because it cannot safely expel exhaust fumes out of the external flue pipe.
Your boiler has encountered a computer software error while trying to start up and cannot function.
Your boiler's internal computer has suffered a major electrical failure and is no longer able to control the heating system.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes