19 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Tap any card for details
Your boiler has detected that water is not flowing through it properly, which is likely because there is trapped air in the system or a sensor is misreading the flow.
Your boiler has stopped working because a sensor that monitors its temperature is giving a faulty signal, causing the system to shut down for safety.
Your boiler has lost the signal from one of its internal temperature sensors, causing it to stop firing because it does not know how hot it is.
Your boiler is struggling because a sensor that monitors the temperature of the returning water has developed an electrical fault and is sending incorrect data to the control board.
Your boiler has lost communication with a sensor that monitors the water returning to it, which prevents the system from heating your home properly.
Your boiler's electronic control panel is failing to communicate with the internal system, which prevents the heating and hot water from functioning correctly.
Your boiler has detected an internal electronic malfunction and has shut itself down to prevent damage, meaning you currently have no heating or hot water.
Your boiler has detected an issue with its incoming electrical power supply, meaning it isn't getting the steady voltage it needs to operate safely.
Your boiler has detected an internal electronic error that is preventing it from starting safely.
Your boiler has detected an internal electronic error that is preventing it from starting up correctly.
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Your boiler detects a flame before it has even started the ignition process, which is a safety conflict that prevents it from firing up.
Your boiler has failed to ignite or stay lit, meaning you currently have no heating or hot water.
Your boiler has stopped working because it cannot detect the internal fan that safely clears combustion gases.
Your boiler has detected that a gas valve inside the unit is not shutting off as quickly as it should, which triggers a safety shutdown to prevent any risk.
Your boiler has detected a communication or power issue with its internal fan, which is crucial for safely venting exhaust gases.
Your boiler has stopped working because the internal fan that safely removes exhaust gases is not spinning up to the correct speed.
Your boiler's internal computer has crashed due to an ignition failure or electrical interference, preventing it from starting the burner.
Your boiler has stopped working because it has detected a major internal system error that prevents the burner from operating safely.
BoilerFaultCodes