26 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler has detected that it has become too hot and has automatically shut itself down to prevent damage.
Your boiler has detected an issue with the fan system, which is preventing it from safely clearing waste gases and starting the ignition process.
Your boiler has failed to ignite the flame reliably and has stopped trying for your safety.
Your boiler is failing to create the spark needed to light the flame, which means your heating and hot water will not work.
Your boiler is struggling to switch between providing heating and hot water because an internal mechanical valve has become stuck or failed.
Your boiler has stopped working because water is not moving around the system correctly, likely due to a pump failure or a blockage.
Your boiler is failing to detect the flame needed to heat your water, which is causing the system to shut down for safety.
Your boiler has detected an electrical safety issue related to the grounding of the system, which is preventing it from running safely.
Your boiler is struggling to confirm that a steady flame has been established, causing it to shut down for safety.
Your boiler has attempted to light but it cannot detect a flame, meaning it has locked itself out for safety.
Your boiler's electronic control board is having trouble sending power to the ignition system, meaning it cannot safely start the flame.
Your boiler has detected a blockage or reduced water flow, often caused by a dirty filter or debris in the heating pipes.
Your boiler has got too hot and has shut itself down as a safety precaution to prevent damage.
Your boiler is not communicating correctly with your wall thermostat, meaning the heating may not turn on when you want it to.
Your boiler has a fault with the electronic component that controls the size of the flame, meaning it cannot heat your water or home correctly.
Your boiler has detected a problem with the internal thermometer that monitors the water temperature for your radiators, meaning it cannot heat your home reliably.
Your boiler has detected that the water pressure inside the system is not at the correct level to operate safely.
Your boiler is having trouble switching between heating your radiators and providing hot water because an internal switch has failed to trigger.
Your boiler has lost its connection to the external timer or there is a communication error with its internal clock settings.
Your boiler has switched itself off for safety reasons, which usually means it has failed to ignite or has detected a critical internal error.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Your boiler is failing to light the gas flame, which means you currently have no heating or hot water.
Your boiler has detected that the water pressure is too low to operate safely, causing it to shut down.
Your boiler has detected that water is not moving through the system properly, which is often caused by low water pressure.
Your boiler has sensed it is getting too hot and has shut itself down for safety.
Your boiler has performed a self-diagnostic check and stopped working because it detected an internal error that requires a reset or professional inspection.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes