29 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 stopped working because it has detected a blockage in the burner or because the electrical supply voltage coming into your home is too low.
Your boiler has temporarily stopped working because it has detected an issue with the temperature sensor or its wiring, preventing it from firing safely.
Your boiler has detected an electrical fault with the external weather sensor on the outside of your property, meaning it may not adjust its temperature correctly based on the weather outside.
Your boiler has lost connection to the weather sensor outside, meaning it cannot automatically adjust your heating based on the outdoor temperature.
Your boiler has temporarily stopped working because it cannot accurately read its internal water temperature, usually due to a faulty sensor or loose wiring.
Your boiler has temporarily stopped working because it has detected a broken or faulty connection inside its main water temperature sensor.
Your boiler is unable to heat your hot water cylinder because it has detected an electrical fault with the cylinder temperature sensor.
Your boiler has stopped heating your hot water because a temperature sensor has developed an electrical fault.
Your boiler has detected a potential blockage or a fault with one of its temperature sensors, which causes it to stop operating for safety.
Your boiler has temporarily stopped heating your hot water cylinder because it has lost the signal from the hot water temperature sensor.
Your boiler is unable to provide hot water because it has detected a broken wire or faulty connection on the hot water temperature sensor.
Your boiler has detected that a temperature sensor inside the exhaust system is not sitting in the correct position.
Your boiler has lost communication with its smart thermostat or controller, meaning it cannot properly receive instructions to heat your home.
Your boiler has detected a potential issue with the temperature sensor in the exhaust flue, causing it to lock out for safety.
Your boiler has entered a temporary safety mode because its internal brain detected an internal glitch, and it needs a quick restart to try and clear it.
Your boiler has temporarily stopped working because it has detected an issue with the sensor that measures the temperature of the exhaust gases coming from the flue.
Your boiler has temporarily shut down for safety because a vital internal temperature control has detected a potential overheating risk.
Your boiler has stopped working because it cannot safely detect the flame, which usually points to a sensor or internal blockage issue.
Your boiler has detected a serious internal communication or control system fault, meaning it has shut down safely to prevent further issues.
Your boiler has temporarily stopped working because it has gotten too hot inside, usually due to low water pressure or trapped air in the system.
Your boiler has temporarily shut down because it got too hot, which usually happens if there is trapped air in the system or the water pressure is too low.
Your boiler has detected a flame signal before it has even tried to light, which prevents it from starting up safely.
Your boiler has stopped working because it cannot detect a flame to safely light the gas.
Your boiler has safely shut down because the gas valve did not close quickly enough, requiring a Gas Safe registered engineer to inspect the gas supply and internal controls.
Your boiler has stopped working because the internal fan is failing to spin fast enough when trying to start up.
Your boiler has stopped working because it cannot confirm that the internal fan has safely turned off before starting up.
Your boiler has locked out because it cannot properly communicate with its internal air fan, meaning it cannot safely clear combustion gases to ignite.
Your boiler has stopped working because it cannot safely ignite or control the burner, but you can try a simple reset before calling for help.
Your boiler has stopped working because the internal control unit has detected a problem with how the burner starts or operates.
Monthly cover means no unexpected bills when your boiler breaks down.
Affiliate links. We may earn a commission at no extra cost to you.
BoilerFaultCodes