28 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler has lost communication with its gas control unit, meaning it cannot safely ignite to provide heating or hot water.
Your boiler has lost signal from the sensor that monitors the temperature outside your home, usually because of a wiring fault or a broken sensor.
Your boiler is struggling to pump water around the system, often because the water pressure is too low or there is a blockage or air bubble preventing flow.
Your boiler has detected that water is still circulating or a sensor is stuck even when the pump should be off.
Your boiler has detected an electronic communication error with the gas valve, meaning it cannot safely light the burner to provide heat or hot water.
Your boiler has lost its ability to accurately measure the temperature of the water used to heat your radiators, meaning your heating will likely stop working.
Your boiler has stopped working because a sensor that monitors the temperature of the exhaust gases has failed or is reporting an error.
Your boiler has detected an issue with the sensor that monitors the temperature of the water returning from your radiators.
Your boiler's temperature sensor for hot water has developed a fault or a loose connection, meaning the system cannot accurately measure how hot the water is.
Your boiler has detected that water is not circulating correctly before the burner lights, which usually means there is a blockage or a pump issue.
Your boiler has shut down because it grew too hot too quickly, usually because the water inside isn't circulating properly.
Your boiler has detected that there is not enough water pressure in the system to operate safely, causing it to shut down.
Your boiler is struggling to move heated water through the system effectively, which is causing it to stop for protection.
Your boiler has lost its flame multiple times during operation and has safely shut down to prevent a malfunction.
Your boiler is starting up but struggling to keep the flame alight, causing it to shut down for safety purposes.
Your boiler has shut down because a safety sensor has detected that the exhaust gases are getting too hot, which can be caused by a blockage or an internal component failure.
Your boiler has failed to light a flame, which is usually caused by a temporary interruption in the gas supply or a frozen condensation pipe.
Your boiler is trying to start but cannot detect a flame, meaning it is failing to ignite after several attempts.
Your boiler has lost its gas supply or detected an internal error, causing it to shut down for safety.
Your boiler has detected that water is circulting poorly or heating up too quickly, causing the temperature sensors to provide unusual readings.
Your boiler has detected an issue with its internal fan, which means it cannot safely exhaust fumes and has stopped working as a safety precaution.
Your boiler has detected a problem with the sensor that monitors the temperature of your hot water, meaning you likely have no hot water or it is inconsistent.
Your boiler has detected that there is not enough water circulating inside it while the burner is on, causing it to overheat rapidly and shut down for safety.
Your boiler has detected an issue with the electrical frequency coming from the mains power supply or a fault within its internal control board.
Your boiler has detected an issue with the sensor that monitors the temperature of your hot water, meaning your taps may not get warm.
Your boiler thinks a flame is present even though it hasn't been told to light, causing the system to shut down for safety.
Your boiler is not receiving enough electrical power from the mains supply to operate safely.
Your boiler has detected that the water pressure is too low to operate safely and has temporarily stopped working.
BoilerFaultCodes