28 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler has lost its connection to the sensor that monitors the temperature of the water leaving the unit, usually causing the system to stop working for safety.
Your boiler has lost its connection to the sensor that monitors the temperature of the water leaving the unit, causing it to shut down for safety.
Your boiler has lost connection with the sensor that monitors the water returning to the unit, causing it to shut down for safety.
Your boiler has detected a problem with the temperature sensor that monitors the water returning from your radiators, causing it to stop heating for safety.
Your boiler has stopped working because it has detected an electrical fault with the internal sensor that monitors the temperature of the water leaving the unit.
Your boiler has detected an electrical fault with the sensor that monitors water returning from your radiators, causing the system to shut down for safety.
Your boiler has lost its connection to the hot water tank sensor, meaning it cannot tell how hot your water is and may stop providing it.
Your boiler has switched itself off because it has detected that the internal temperature has become too hot and reached a dangerous level.
Your boiler has detected that there is not enough water pressure inside the system to operate safely, causing it to shut down to prevent overheating.
Your boiler has stopped working because the water isn't circulating properly between the pipes, causing a sudden and unsafe temperature gap.
Your boiler is heating up much too fast because there isn't enough water moving through the system to carry the heat away.
Your boiler has detected that the water pressure is too low or a safety switch has disconnected, causing the system to shut down for protection.
Your boiler has detected a flame when there shouldn't be one, which means the safety system has locked the unit down to prevent an unsafe situation.
Your boiler has tried to light several times but has been unable to establish a flame, meaning you have no heating or hot water.
Your boiler was working but the flame has unexpectedly gone out, causing the system to shut down for safety.
Your boiler’s air fan is not spinning at the correct speed to safely push exhaust fumes out of the flue, causing the system to shut down for safety.
Your boiler's internal communication system is experiencing a power drop, meaning the main control board cannot talk to your thermostat or other smart controls.
Your boiler has detected an electrical fault connected to the component that controls the gas flow, meaning it cannot safely light the burner.
Your boiler is struggling to talk to the gas valve, which means it cannot safely light the flame to provide heating or hot water.
Your boiler has detected that the gas valve is not closing as quickly as it should, preventing the unit from shutting down safely and causing it to lock out.
Your boiler's internal computer brain has suffered a memory error and can no longer process the data it needs to run safely.
Your boiler has detected a communication error between its internal sensors and the main control board, preventing it from heating your home safely.
Your boiler's internal control board has become too hot to operate safely and has shut down to prevent damage.
Your boiler's electronic control board is having trouble communicating with the flame sensor, meaning the system cannot safely confirm if the burner is lit.
Your boiler's control board has lost its identity settings, meaning the internal computer no longer recognizes which model of boiler it is supposed to be controlling.
Your boiler's temperature sensor is stuck on a single reading, meaning the system cannot safely tell if the water is heating up correctly.
Your boiler is struggling to accurately measure water temperature because its sensors are sending conflicting or incorrect signals.
Your boiler is unable to detect the necessary internal water pressure increase required to start the heating process.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes