40 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler's main control chip has lost communication with the circuit board, essentially meaning the brain and body are no longer speaking to each other.
Your boiler has lost communication with its internal computer chip, meaning the main control board no longer recognizes the specific model it is supposed to be operating.
Your boiler is not broken; it is simply in a special service mode used by engineers when they are preparing to replace internal parts.
Your boiler has detected that the water pressure inside the system is too low to run safely and has stopped working as a result.
Your boiler is failing to stay lit or cannot detect its own flame, meaning it has shut down for safety and will not provide heating or hot water.
Your boiler has started an ignition process but the flame has gone out, meaning the system has shut down for safety.
Your boiler has detected an issue with the internal fan, which is preventing the system from safely clearing exhaust gases and starting the ignition process.
Your boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, meaning it cannot safely regulate heat.
Your boiler has stopped working because it is having trouble reading the temperature of the water flowing through it, so it has safely shut down to prevent overheating.
Your boiler has detected an issue with the sensor that monitors the temperature of the water returning to the unit, causing it to stop working for safety.
Your boiler has lost the ability to accurately measure the temperature of the water returning to it, so it has safely shut down to prevent overheating.
Your boiler has lost connection with the sensor that monitors the outdoor temperature, making it difficult for the system to adjust its heat settings efficiently.
Your boiler has detected that the electricity supply coming into your home is at a lower voltage than it needs to operate safely.
Your boiler's computer brain has lost its settings or is experiencing an electrical fault, preventing the system from starting up.
Your boiler's computer memory is blank or incorrect, meaning it doesn't currently know how to operate itself.
Your boiler's main internal computer is failing to communicate correctly with its internal control systems, preventing it from safely starting up.
Your boiler has detected that the water temperature sensors are giving conflicting readings, often caused by the flow and return pipes being switched or a sensor failing.
Your boiler is displaying an error code for a feature that isn't actually used on this model, which usually indicates a simple electronic glitch or a programming error.
Your boiler has lit correctly but the flame has gone out unexpectedly, often due to a temporary interruption in the gas supply or a blocked condensate pipe.
Your boiler has detected that the water is heating up too quickly or isn't moving through the system properly, causing it to overheat and shut down for safety.
Your boiler has shut down because the water inside it has become too hot, usually due to a lack of circulation or a blockage in the system.
Your boiler has stopped working because it cannot light a flame, which is often caused by a lack of gas supply or a blocked pipe.
Your boiler has detected a problem with the internal temperature sensor that monitors the water leaving the unit, causing it to shut down as a safety precaution.
Your boiler has stopped working because it can no longer accurately read the temperature of the water inside the unit.
Your boiler has detected a problem with the sensor that monitors the temperature of the water coming back into the unit, causing it to shut down for safety.
Your boiler has lost the ability to read the temperature of the water returning to it, so it has shut down as a precaution to prevent overheating.
Your boiler thinks a flame is present even though it hasn't been safely ignited, causing the system to shut down for safety.
Your boiler's computer brain has lost its settings or is experiencing an electrical fault, preventing the system from starting up.
Your boiler's computer brain has lost its settings or is experiencing an electrical fault, preventing the system from starting up.
Your boiler has tried and failed to start up five times in a short window and has now locked itself out for safety.
Your boiler is struggling to keep its flame lit, which means it cannot heat your water or radiators reliably.
Your boiler is in a standby or programming mode and thinks it has been told to stay switched off.
Your boiler is displaying a service setting notification rather than a breakdown, indicating the internal pump is being told to run at its maximum speed.
Your boiler is displaying a configuration setting rather than a breakdown, indicating the internal pump is set to its standard minimum operating speed.
Your boiler is simply reminding you that its annual service is due soon; it is a notification rather than a breakdown.
Your boiler is not in a fault state; it is simply running in a manual test mode designed for service engineers to check its performance.
Your boiler is currently running a service test at its lowest power setting and this is a status indicator rather than a functional error.
Your boiler is currently set to a professional test mode for servicing and is not in its normal operating state.
Your boiler is currently stuck in its startup or programming sequence and is not yet ready to provide heat or hot water.
Your boiler is performing a routine self-cleaning process to remove air bubbles from the system and is not actually reporting a hardware fault.
BoilerFaultCodes