34 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 is struggling to discharge exhaust fumes safely or is detecting a significant lack of air flow.
Your boiler has detected a sequence of ignition or flame detection errors and has shut itself down for safety.
Your boiler has detected a sequence error or a flame signal where there shouldn't be one, causing the burner to shut down completely for safety.
Your boiler has detected a sequence of ignition or flame detection errors and has shut itself down for safety.
Your boiler is struggling to communicate with the solar panel system used to help heat your water.
Your boiler's outside thermometer has developed a fault, causing the system to 'think' it is 0°C outside and adjust your heating accordingly.
Your boiler is confused about the weather outside because the external sensor has lost its connection, meaning the heating might not adjust correctly to the outdoor temperature.
Your boiler's internal computer has detected a faulty or damaged temperature sensor, preventing the system from accurately measuring how hot the water is.
Your boiler has lost communication with a sensor that monitors the temperature of the water flowing into your heating system, usually because of a loose or damaged wire.
Your boiler has stopped working because its internal temperature sensor has developed an electrical fault and can no longer safely monitor the heat level.
Your boiler has failed to ignite or stay lit, meaning your heating and hot water have stopped working.
Your boiler has stopped working because it cannot accurately measure its own internal temperature due to a broken or disconnected sensor wire.
Your boiler has detected a faulty temperature sensor in one of your heating zones, which is preventing that specific circuit from getting warm.
Your boiler has lost communication with the temperature sensor that controls your second heating circuit, causing that specific zone to stop heating correctly.
Your boiler is unable to heat your hot water because one of the internal temperature sensors has developed an electrical fault.
Your boiler is unable to provide hot water because of a faulty internal sensor that has stopped communicating correctly.
Your boiler is unable to heat your hot water because a sensor responsible for monitoring the cylinder temperature has lost its connection or stopped working.
Your boiler has sensed that the internal pump is malfunctioning or water is not circulating correctly, which has caused the system to stop as a safety precaution.
Your boiler has detected that the water pump is likely stuck or not moving water correctly, which means the system cannot heat up safely.
Your boiler is having trouble communicating with the control kit that manages the heating for your secondary radiator or underfloor heating zone.
Your wall-mounted remote control unit is not communicating correctly with the boiler because of a settings error.
Your boiler is having trouble communicating with an optional external control accessory, meaning it cannot receive or send specific remote commands.
Your boiler is having trouble communicating with its internal pump, which means water cannot circulate properly to heat your home.
Your boiler is having trouble communicating with the internal pump that manages one of your heating circuits, meaning that part of your heating may not be working correctly.
Your boiler has lost connection to one of its internal temperature sensors, which means it cannot accurately monitor the heat for one of your heating zones.
Your boiler has shut down because it cannot safely vent exhaust gases or draw in fresh air, usually due to a blockage in the flue pipe or a hardware failure.
Your boiler is currently running an automated air-release mode to clear trapped air from the system, which is a normal maintenance process.
Your boiler has shut down because it detected that the exhaust gases have become too hot, which is a safety feature to prevent damage or dangerous operation.
Your boiler is failing to light the flame needed to heat your water and radiators, which has caused the system to shut down for safety.
Your boiler has shut down because it is unable to accurately measure the air pressure required for its burner to operate safely.
Your boiler has stopped working because the internal fan is spinning too fast during the startup process, preventing the burner from igniting safely.
Your boiler's internal computer has detected a problem with the burner's ignition system and has shut down as a safety precaution.
Your boiler has detected that the water pressure inside your heating system is too low, so it has automatically paused operation to prevent damage.
Your boiler is currently running an automated air-removal cycle to clear trapped air from the heating system and is not faulty.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes