10 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler is failing to start because it is not detecting electricity or there is not enough water pressure inside the system to operate safely.
Your boiler has lost power or has insufficient water pressure to operate, meaning it cannot provide heating or hot water.
Your boiler has automatically shut down because it has detected that it is getting too hot inside, likely because the water is not circulating as it should.
Your boiler has switched itself off to prevent overheating because the system is getting too hot or the water is not circulating properly.
Your boiler is failing to clear combustion gases properly, so it has safely shut down to prevent any risk.
Your boiler has detected that the internal safety fan isn't moving air properly, so it has shut down for safety.
Your boiler is failing to light the flame needed to heat your water or home, causing the system to shut down for safety.
Your boiler is failing to light the pilot flame or detect a steady flame, meaning it cannot start the heating process.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Your boiler has detected that the water pressure is too low to operate safely and has shut down to prevent damage.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes