31 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Concord CXA
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Your boiler has detected a general internal fault that requires a specialist to correctly identify and resolve.
Your boiler has encountered a general system error that has caused it to shut down for safety reasons to prevent potential damage.
Your boiler has detected a internal system error that has caused it to shut down for safety reasons.
Your boiler has detected an internal safety fault and has stopped operating to ensure your home remains safe.
Your boiler has detected a general internal error that is preventing it from starting up correctly, which will result in you having no heating or hot water until it is fixed.
Your boiler has detected an internal error preventing it from operating, which usually indicates an issue with the main control board or communication between internal parts.
Your boiler has detected a internal system error that has caused it to shut down for safety reasons.
Your boiler has detected a general internal fault that is preventing it from operating, which usually indicates an electronic control or configuration error.
Your boiler has detected a general internal fault that is preventing it from operating safely and effectively.
Your boiler has detected an internal fault that has caused it to shut down for safety reasons to prevent potential damage.
Your boiler has detected a general internal fault that is preventing it from operating safely, causing it to shut down.
Your boiler has detected a general internal error that is preventing it from firing up reliably to provide heating or hot water.
Your boiler has detected a general internal fault that is preventing it from operating safely, requiring a qualified professional to diagnose the specific root cause.
Your boiler has detected a general internal error that is preventing it from operating safely and normally.
Your boiler has stopped working because it cannot confirm that the fan is safely clearing waste gases from the system.
Your boiler is currently taking a short mandatory rest to prevent unnecessary wear and tear on its internal parts.
Your boiler has reached its target temperature and is taking a short, two-minute break to prevent components from wearing out by switching on and off too frequently.
Your boiler has detected that the temperature sensor used to monitor the water inside the unit is broken or sending incorrect signals.
Your boiler's temperature sensor has stopped working correctly, meaning the system can no longer tell how hot the water is and has shut down as a precaution.
Your boiler has tried to start up several times but cannot establish a stable flame to begin heating.
Your boiler has stopped working because it cannot detect a flame, meaning it has safely shut down to prevent gas from flowing without being burned.
Your boiler has stopped working because the internal fan that safely removes exhaust gases is not running correctly.
Your boiler has encountered an internal timing error or electrical communication fault because it didn't enter the correct setup mode when its gas control valves were being linked.
Your boiler has detected that the water levels inside the system are incorrect, or the sensor that monitors the water level is faulty.
Your boiler is unable to light because the internal system that controls the gas flow has stopped working correctly.
Your boiler has unsuccessfully tried to start five times and has now shut itself down for safety reasons to prevent a gas buildup.
Your boiler's outdoor temperature sensor is not communicating correctly, which may affect how efficiently the system adjusts your heating based on the weather.
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Your boiler has stopped heating up because the water is not being pushed through the pipes as it should be.
Your boiler has stopped heating up because the water is not being circulated through the system correctly.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes