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 lost its connection to the sensor that monitors the temperature of your hot water cylinder, meaning it cannot properly manage your hot water supply.
Your boiler has lost communication with the solar heating system or has detected a fault within the solar control unit.
Your boiler's outside temperature sensor has developed an electrical fault, causing the system to behave as if it is exactly 0°C outdoors regardless of the actual weather.
Your boiler has lost connection to its outdoor sensor, causing it to think it is freezing outside and potentially making your radiators warmer than necessary.
Your boiler has lost its connection to the temperature sensor that monitors the main water flow, likely due to a faulty electrical component or sensor.
Your boiler has lost connection with a temperature sensor that monitors the main water flow, meaning it cannot accurately regulate how much heat to send to your radiators.
Your boiler has stopped working because its internal temperature gauge has failed, causing the system to lock the burner for safety.
Your boiler has stopped working because it can no longer accurately measure its own internal temperature due to a broken wire or faulty sensor.
Your boiler has detected a technical fault with a sensor on one of your heating zones, which means that specific part of your heating will likely shut down to prevent damage.
Your boiler is unable to heat your water because the temperature sensor for your hot water cylinder has failed or has a wiring fault.
Your boiler is unable to heat your hot water cylinder because it has detected a faulty or short-circuited temperature sensor.
Your boiler is unable to heat your water because the sensor that monitors your hot water cylinder temperature has lost its electrical connection.
Your boiler is having trouble communicating with your wall-mounted room thermostat because the settings weren't configured correctly during installation or after a power cut.
Your boiler is struggling to communicate with its internal pump, which means it cannot properly move heated water around your system.
Your boiler is having trouble communicating with the internal pump that moves water around your second heating zone, which may prevent some of your radiators from getting hot.
Your boiler is having trouble 'talking' to an external accessory, such as an extra heating controller or a smart home module.
Your boiler is struggling to breathe because the pipe that vents exhaust gases outside or brings fresh air in is obstructed.
Your boiler is failing to light the flame properly, meaning it cannot provide heating or hot water for your home.
Your boiler has detected a problem with internal pressure readings, which means it cannot safely confirm the correct flow of air for combustion.
Not faults — these are normal operating states. Tap to expand.
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