30 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler is trying to start up, but it is unable to light the flame needed to produce heat.
Your boiler has detected that it is running too hot and has automatically shut down to prevent any internal damage.
Your boiler has detected that the exhaust gases are becoming dangerously hot and has automatically shut down to prevent damage or overheating.
Your boiler has detected an electrical issue with the internal component that controls the gas supply, prevent it from firing up safely.
Your boiler is struggling to detect the movement of water, which will likely prevent your heating or hot water from working properly.
Your boiler is struggling to accurately measure the temperature of the hot water it produces, which typically results in the hot taps running cold.
Your boiler has hit its safety limit for automatic restarts after trying to fix a persistent internal error too many times.
Your boiler has detected that the water pressure level is too low to safely operate, so it has shut itself down to prevent damage.
Your boiler is having trouble reading the temperature of the cold water coming into the system, which may cause your hot water to fluctuate in temperature.
Your boiler’s internal computer is confused because its current settings do not match the physical pipe setup it detects.
Your boiler has detected an issue with the internal fan that pushes exhaust gases out of your home, so it has shut down as a safety precaution.
Your boiler has detected a flame signal when it is not actually burning, acting as a safety precaution to prevent potential gas buildup.
Your boiler is struggling to accurately measure the temperature of the water coming back into the system, so it has safely shut down to prevent overheating.
Your boiler has detected that a button on the control panel is being held down or is stuck, which is preventing it from operating correctly.
Your boiler has detected an issue with the sensor that monitors the exhaust gas temperature and has shut down for safety reasons.
Your boiler has lost communication with its smart thermostat, meaning it cannot receive instructions to turn on your heating or hot water.
Your boiler is failing to start because it is not receiving enough electrical power from your home's main supply.
Your boiler briefly detected a flame but could not keep it lit, so it is automatically trying to restart itself.
Your boiler is repeatedly shutting down because the burner flame keeps going out, potentially due to strong wind affecting the outside flue pipe.
Your boiler has identified that the water is heating up or circulating much faster than it should be, causing the system to shut down for safety.
Your boiler is overheating its exhaust system and has automatically slowed down to prevent damage, but it may stop working entirely if the temperature does not drop.
Your boiler has lost its wireless connection to your room thermostat, meaning it doesn't know when to turn your heating on or off.
Your boiler is unable to circulate water effectively because the internal pump is either jammed or has suffered an electrical failure, meaning the boiler cannot heat your home or water.
Your boiler is struggling to pump water around your radiators because there is likely air trapped inside the system or a blockage in the pipes.
Your boiler is struggling to accurately measure the temperature of the water circulating inside it, which has caused it to stop heating your home as a safety precaution.
Your boiler is struggling to read its own temperature because one of its internal monitoring sensors is likely faulty or disconnected.
Your boiler's temperature sensors are providing conflicting or faulty readings, which is preventing it from heating your water and radiators safely.
Your boiler has detected that the exhaust gases leaving the flue are getting too hot, so it has shut down to prevent any damage.
Your boiler is struggling to detect the temperature of the cold water coming into the system, which means it may fail to provide consistent hot water to your taps.
Your boiler has detected that the flame inside has gone out unexpectedly, so it has shut down for safety reasons to prevent leaking gas.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes