46 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler has lost the signal from one of its internal temperature sensors, causing it to shut down for safety.
Your boiler has lost the signal from the sensor that monitors the water temperature returning to the unit, causing it to stop heating as a safety precaution.
Your boiler's internal thermometer has developed a fault and can no longer tell how hot the water is, causing the system to shut down for safety.
Your boiler has stopped working because it is unable to accurately measure the temperature of the water returning to it, preventing it from heating safely.
Your boiler is struggling to accurately measure the temperature of the water stored in your hot water cylinder because there is an electrical fault with the sensor cable.
Your boiler has detected that it is running too hot and has automatically turned itself off to prevent any damage or safety issues.
Your boiler has stopped working because the amount of water inside your heating system has dropped below the minimum level required to operate safely.
Your boiler has detected that the water is heating up significantly faster than it can be moved around your system, forcing it to shut down to prevent internal damage.
Your boiler has detected that the water inside is heating up far too quickly, so it has shut itself down to prevent any damage or overheating.
Your boiler has detected that the exhaust gases are becoming far too hot and has automatically switched itself off to prevent damage or dangerous overheating.
Your boiler has detected what it thinks is a flame while the gas is supposed to be turned off, so it has shut itself down as a precaution.
Your boiler is failing to light because it cannot detect a flame, meaning you currently have no heating or hot water.
Your boiler is attempting to light but is failing to stay on, meaning you currently have no heating or hot water.
Your boiler has detected that the internal fan responsible for safely venting exhaust gases is not spinning, so it has shut down to prevent unsafe operation.
Your boiler is struggling to breathe properly because there is a blockage or a problem with the pipes that bring in fresh air and push out exhaust fumes.
Your boiler has detected an issue with the sensor that measures incoming cold water, which usually means the sensor or its wiring needs attention.
Your boiler has lost its secure communication signal between its internal controls, meaning it cannot operate properly.
Your boiler has detected an issue with the valve that controls the gas supply, meaning it has safely shut down to prevent unsafe operation.
Your boiler has detected an issue with the internal gas valve failing to shut down properly, which requires an inspection by a qualified professional.
Your boiler has detected an internal computer memory error or a problem with the ignition system, so it has safely shut down to prevent damage.
Your boiler has detected a sudden electrical or temperature reading error, meaning it has temporarily stopped working to keep your home safe.
Your boiler's main control board has become too hot or registered an internal temperature error and has safely shut down to prevent damage.
Your boiler has detected an internal electronic error regarding how it reads the flame, meaning it has safely shut down to prevent any risk.
Your boiler has detected an unstable flame or a problem with the gas and air supply, causing it to lock out for safety.
Your boiler has lost its unique identification memory, usually because a main circuit board was replaced without being programmed properly.
Your boiler has temporarily stopped working because it cannot accurately read the temperature of the water flowing through the system.
Your boiler has temporarily stopped working because it is getting incorrect temperature readings from its internal sensors, meaning it cannot safely regulate its heat.
Your boiler has detected that the water pressure reading is too low or that there is a problem with the sensor measuring it, which causes the system to stop working for safety.
Your boiler has detected that the water pressure reading is abnormally high or that the sensor measuring it is faulty.
Your boiler has detected low water pressure or a circulation issue, meaning it cannot safely ignite to provide heating or hot water.
Your boiler has automatically shut down because an internal safety device detected excessively high temperatures inside the unit.
Your boiler has detected an issue with the safety flap in the exhaust flue or the condensate drainage system, meaning it has temporarily stopped working to keep your home safe.
Your boiler has temporarily stopped providing hot water because it is not receiving the correct temperature readings from a sensor.
Your boiler has detected that there is not enough water inside the system or the temperature sensors are not reading correctly.
Your boiler has detected an error with its internal temperature sensors, which means it cannot safely regulate how hot the water is getting.
Your boiler has detected that the temperature monitoring sensors inside have been fitted to the wrong pipes, meaning it cannot accurately track the heating water.
Your boiler has safely shut itself down because it detected an internal temperature or water flow problem.
Your boiler is unable to safely light its internal burner because of a connection problem with the ignition system.
Your boiler has detected an issue with the internal gas valve connection, meaning it cannot safely regulate the gas supply to ignite.
Your boiler has lost its electrical connection to the internal water pump, which means it cannot circulate water to heat your home or provide hot water safely.
Your boiler's computer is unable to complete its internal startup check, meaning it cannot safely operate and has shut down to protect the system.
Your boiler is currently running a routine automatic process to clear trapped air from its internal pipes to help it heat your water and radiators more efficiently.
Your boiler is currently just running a routine internal check as it starts up the heating system, so this is a normal status message rather than a breakdown.
Your boiler is currently running through a routine self-check as it prepares to ignite the flame.
Your boiler is currently in a manual testing mode used by engineers to check exhaust gases and is not indicating an actual breakdown.
Your boiler is currently in a manual mode used for filling the system with water or draining it, rather than operating in normal heating mode.
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BoilerFaultCodes