27 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Keston Heat
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Your boiler has detected an internal error it does not recognise and has shut itself down as a safety precaution.
Your boiler has switched itself off because the water inside is running much hotter than it should be.
Your boiler has detected that the water returning to it is dangerously hot and has shut down to prevent damage or overheating.
Your boiler has detected that hot water is flowing in the wrong direction, indicating a potential issue with your heating system's pump or sensor wiring.
Your boiler is overheating because water isn't moving through the system properly, likely due to trapped air or a blockage.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Your boiler has detected that the internal fan responsible for venting exhaust gases is not communicating with the system, so it has safely shut down to prevent unsafe operation.
Your boiler's air circulation fan is not communicating properly with the control system, which prevents the unit from starting safely.
Your boiler is struggling to pump water around your heating system effectively, meaning it cannot move the hot water away from its internal components quickly enough.
Your boiler is momentarily pausing because it has not yet received a signal that the internal fan is spinning up as expected.
Your boiler has detected that it is running too hot or that the pressure in your heating system is too low, so it has purposefully shut down to protect itself from damage.
Your boiler has detected a flame inside when it is switched off, which is a safety lockout preventing the unit from starting.
Your boiler is failing to light the flame needed to produce heat or hot water.
Your boiler is failing to detect the flow of gas required to ignite the burners, meaning it cannot safely produce heat or hot water.
Your boiler has lost its memory of a previous error because it was switched off and back on again while it was already trying to protect itself.
Your boiler's computer is experiencing a internal processing error and needs to be reset or potentially replaced to get the system working again.
Your boiler has detected that it is getting dangerously hot and has shut itself down to prevent damage to the internal system.
Your boiler has detected that the water inside has become dangerously hot and has shut itself down to prevent damage.
Your boiler has detected that the water returning to it is too hot, which suggests the water isn't moving through your radiators properly and the system is overheating.
Your boiler is struggling to pump water around your heating system quickly enough, causing the water inside to get hot too fast and triggering a safety shutdown.
Your boiler has stopped working because the mechanical fan that pushes waste gases outside is not spinning as it should.
Your boiler is struggling to move heat around your home because the water is not flowing efficiently between the heater and your radiators.
Your boiler has stopped working because it is unable to accurately read the temperature of the water flowing through the system due to a faulty sensor connection.
Your boiler has lost the ability to accurately measure the temperature of the water returning to it, so it has shut down as a precaution to prevent overheating.
Your boiler has lost the ability to measure the temperature of the water flowing through it because a sensor connection has failed or disconnected.
Your boiler has lost the signal from one of its internal temperature sensors, meaning it cannot correctly measure the temperature of the water returning to the system and has stopped working as a safety precaution.
Your boiler has stopped heating because the water pressure inside the system has dropped too low.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes