47 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler has automatically turned itself off because the water inside it has become dangerously hot.
Your boiler has failed to light because it cannot detect a steady gas supply, so it has safely shut down to prevent gas from leaking into your home.
Your boiler has failed to light the flame after three attempts, meaning it is currently unable to provide heating or hot water.
Your boiler has detected that it is overheating significantly and has shut itself down to prevent any damage or safety issues.
Your boiler is failing to light the flame consistently despite multiple attempts, so it has shut down as a safety precaution.
Your boiler has detected that a flame is still burning inside even though it has commanded the gas supply to turn off.
Your boiler has detected a flame inside the combustion chamber before it actually turned on the gas supply, implying a potential sensor or ignition system error.
Your boiler is failing to detect that water is moving through the system, so it is switching off to prevent damage.
Your boiler has detected an issue where it thinks water is still flowing even when it should have stopped, which is preventing it from operating correctly.
Your boiler has detected that the internal fan responsible for safely venting exhaust gases is not spinning or communicating correctly, causing the system to stop working as a safety precaution.
Your boiler's main control computer is experiencing a software or internal communication error and cannot safely operate the system.
Your boiler has failed to start up because it could not light the internal flame after several attempts.
Your boiler is failing to ignite because it cannot detect that the water is warming up after a few attempts, meaning you currently have no heating or hot water.
Your boiler has switched itself off because the water inside it has become dangerously hot and is overheating.
Your boiler is repeatedly failing to stay lit, so it has safely shut down to prevent the release of unburnt gas.
Your boiler has detected that a flame is still burning inside even though it has commanded the gas supply to shut off.
Your boiler has detected a flame inside when it hasn't asked for one, which suggests a dangerous internal sensor or electrical fault.
Your boiler has detected that water is not circulating properly when there is a demand for heat or hot water.
Your boiler is struggling to register that you've turned on a hot water tap, so it isn't starting up to provide hot water or heating.
Your boiler is unable to clear fumes properly because the internal mechanism that pushes air through the flue is not working.
Your boiler's internal computer is experiencing a major communication error and can no longer safely control the heating system.
Your boiler has detected an abnormally high temperature inside the system even though it isn't currently trying to heat your home.
Your boiler is struggling to accurately detect the temperature of the hot water because a sensor connection has failed or disconnected.
Your boiler has developed a faulty sensor that monitors the temperature of your hot water, causing it to stop producing hot water correctly.
Your boiler has lost the connection to the temperature sensor responsible for your underfloor heating, so it has stopped these heaters from working to prevent them from getting too hot.
Your boiler has detected a flame signal even though it is trying to turn the gas off, which indicates a serious safety issue with the internal control system.
Your boiler has detected that the electricity supply wires have been connected in the wrong order, preventing it from operating safely.
Your boiler is struggling to detect a steady stream of electricity, which is preventing it from starting up properly.
Your boiler is failing to detect the flame correctly, so it has safely shut itself down to prevent any issues.
Your boiler has lost its ability to measure the temperature of the water circulating through your radiators, so it has safely shut down to prevent overheating.
Your boiler has lost the ability to read the temperature of the water returning to it, so it has shut down to prevent potential overheating.
Your boiler has stopped working because it is unable to accurately measure the temperature of the water being sent to your radiators, causing it to shut down for safety.
Your boiler is struggling to accurately measure the temperature of the water circulating back from your radiators, so it has shut down as a precaution to prevent overheating.
Your boiler's main computer control panel is experiencing a general internal failure, meaning the system cannot safely regulate your heating or hot water.
Your boiler has sensed that the water inside is dangerously hot even though it is meant to be switched off, which is a significant safety precaution.
Your boiler has lost the signal from the sensor that measures your hot water temperature, so it cannot safely heat the water for your taps.
Your boiler's hot water temperature sensor is sending a faulty signal, meaning your unit cannot accurately detect the temperature of your tap water.
Your boiler is struggling to read the temperature for your underfloor heating system because a connection has been lost or a sensor has failed.
Your boiler has detected a flame when it should be turned off, which indicates a potential safety issue with the gas control system.
Your boiler has detected that the electricity supply wires have been connected the wrong way around, preventing the system from starting safely.
Your boiler is struggling to process the electricity supplied to it, which is likely caused by an unstable power source or an internal failure in the control unit.
Your boiler has detected an issue with the component that monitors the flame, preventing it from starting safely.
Your boiler has lost the ability to measure the temperature of the water circulating through your radiators, so it has safely shut down to prevent overheating.
Your boiler has lost the signal from one of its internal temperature sensors, causing it to stop heating to prevent internal damage.
Your boiler has stopped working because a sensor that measures the water temperature is sending an incorrect electrical signal, causing the system to shut down to prevent overheating.
Your boiler has lost the ability to accurately measure the temperature of the water returning to it, so it has shut down to prevent potential overheating.
Your boiler's main computer control panel is experiencing a general communication error, preventing it from starting safely.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes