18 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler's internal temperature sensors have failed their automatic safety check, causing the system to stop working for safety.
Your boiler has likely stopped working because it has overheated due to trapped air or a pump that isn't circulating water properly.
Your boiler has detected a communication fault or a hardware failure with its internal safety sensors, meaning it cannot operate safely.
Your boiler is failing to light the internal burner, which means it cannot produce any hot water or heating.
Your boiler is struggling to keep its internal flame lit, which means it will stop providing heating and hot water to keep you safe.
Your boiler has detected an issue with the ignition process and has safely shut itself down to prevent gas from flowing without a flame.
Your boiler has stopped working because the fan that clears away waste gases is not spinning at the speed the system expects.
Your boiler has detected trapped air inside the pipes or a sensor issue, which is preventing it from heating your water correctly.
Your boiler has detected trapped air in the system or a faulty temperature sensor, causing it to stop heating to prevent damage.
Your boiler has detected trapped air inside the pipes or a sensor issue, which is preventing it from heating your water correctly.
Your boiler has detected trapped air in the system or a faulty temperature sensor, causing it to stop heating properly to prevent overheating.
Your boiler has detected trapped air in the pipes or a fault with the sensor that monitors water temperature, causing the system to stop working to avoid overheating.
Your boiler's internal temperature sensor has stopped sending information correctly, which means the system cannot monitor heat levels safely and has shut down.
Your boiler has detected a problem with one of its internal temperature sensors, meaning it cannot accurately monitor the water flow.
Your boiler has stopped working because one of its internal temperature sensors is unable to send a correct reading to the control board.
Your boiler has detected a faulty internal temperature sensor which is preventing it from monitoring the water heat levels correctly.
Your boiler has stopped working because one of its internal temperature sensors has failed or has a loose connection.
Your boiler has lost connection with the sensor that measures the temperature outside, which may cause your heating to respond incorrectly to the weather.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes