46 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler has detected that the exhaust gases are not escaping correctly, which could lead to harmful fumes entering your home.
Your boiler has detected that the water pressure is too low to operate safely and has shut down to prevent damage.
Your boiler has detected that the water pressure inside the system is too high, often caused by overfilling or a valve left slightly open.
Your boiler's hot water sensor has failed or has a bad connection, meaning the system cannot accurately monitor the temperature of the water coming out of your taps.
Your boiler has stopped working because it cannot accurately measure the temperature of the water leaving the unit.
Your boiler is failing to light the gas or cannot detect that it has successfully lit a flame.
Your boiler has switched itself off because it has detected that it is getting too hot, which is a safety mechanism to prevent damage.
Your boiler is struggling to detect a flame, which means it cannot safely light itself to provide heating or hot water.
Your boiler has stopped working because water is not moving through the internal pipes and radiators as it should.
Your boiler has detected an issue with an internal temperature sensor, which usually means the system is confused about how it has been set up or a wire has come loose.
Your boiler has lost communication with the component that controls the gas flow, meaning it cannot light the flame to provide heating or hot water.
Your boiler is confused about its internal settings and thinks it is a different model, causing it to shut down for safety.
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 gases, and it has shut down as a safety precaution.
Your boiler has stopped working because it cannot communicate with the internal fan, which is essential for clearing waste gases.
Your boiler has detected that its internal temperature sensors are giving conflicting readings, causing it to shut down as a safety precaution.
Your boiler has stopped working because water that normally drains away is backed up, often due to a blocked or frozen exterior pipe.
Your boiler has been manually reset too many times in a short period and has temporarily locked itself for safety.
Your boiler has detected a problem with the sensor that monitors water temperature returning to the unit, causing it to stop for safety.
Your boiler has detected that the electricity supply coming into your home is too low for it to operate safely and has shut down to protect the internal electronics.
Your boiler has detected an issue with the electrical power timing coming into your home, which is preventing it from running safely.
Your boiler is failing to keep a steady flame alight and has shut down for safety after multiple failed attempts.
Your boiler has detected that one of the buttons on the control panel is stuck or faulty, which is preventing the system from operating correctly.
Your boiler has lost its connection to your smart thermostat or external control panel, meaning it cannot receive the correct signals to turn on and off.
Your boiler is failing to light because its internal computer and gas control parts are not communicating correctly.
Your boiler has shut down because the water is getting too hot too quickly, usually because it isn't circulating through the system properly.
Your boiler has locked itself because it detected an unusual temperature reading and needs to run a self-test to recalibrate its internal sensors.
Your boiler has detected that a temperature sensor is not sitting correctly on its pipe, preventing it from monitoring heat levels accurately.
Your boiler has detected a problem with one of the internal temperature sensors used to monitor the water leaving the unit, which is preventing it from running safely.
Your boiler has detected an electrical issue with the gas control valve, preventing it from safely lighting the burner.
Your boiler has detected an electrical issue with the gas valve system, meaning it cannot safely control the fuel supply to stay alight.
Your boiler has detected an internal electrical problem with the gas valve control system and has shut down for safety.
Your boiler has detected an internal communication error with the gas valve system, meaning it cannot safely control the fuel flow to stay alight.
Your boiler has detected an issue with the air or gas mixture during the ignition process and has locked itself out for safety.
Your boiler has shut down because it has failed to ignite or maintain a flame several times in a row.
Your boiler is struggling to burn gas correctly, which is causing it to stop running as a safety precaution.
Your boiler is not receiving enough gas to operate correctly, which is likely caused by an issue with your external gas supply or a blockage in the pipework.
Your boiler's internal computer has encountered a critical electronic failure and has shut itself down to protect its own circuits.
Your boiler is struggling to maintain a steady flame and has shut down as a safety precaution.
Your boiler is having trouble managing the air and gas mixture required for a safe flame, meaning it cannot start up correctly.
Your boiler is having trouble managing the correct mixture of air and gas required for a safe and efficient flame.
Your boiler is struggling to achieve the correct flame or heat output, meaning it can no longer operate safely or efficiently.
Your boiler is struggling to keep a steady flame alight, causing it to shut down for safety.
Your boiler has shut down because it cannot safely expel exhaust fumes, usually due to a blockage in the outdoor flue pipe.
Your boiler has encountered an internal software error while trying to start up and cannot clear itself.
Your boiler's internal computer has suffered a critical failure and can no longer control the heating or hot water safely.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes