20 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
This boiler uses LED flash patterns
Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →
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Your boiler has shut down because the water inside is getting too hot, too quickly, or cannot circulate properly through your heating system.
Your boiler has lost the ability to accurately measure the temperature of the water circulating inside it, so it has shut down as a precaution to prevent damage.
Your boiler has detected that an external safety control, such as a heating programmer or a smart thermostat, is not communicating with or is disconnected from the unit.
Your boiler has switched itself off because it has become dangerously hot inside, likely due to a blockage in the water flow or a mechanical internal fault.
Your boiler has stopped because it cannot keep the internal fire lit, meaning you currently have no heating or hot water.
Your boiler is trying to start up but is failing to light the internal flame, which means you currently have no heating or hot water.
Your boiler's internal computer is struggling to talk to its internal parts, meaning it has paused operations as a safety precaution until the signal issue is resolved.
Your boiler is having trouble breathing because a part responsible for moving air and fumes is not working correctly, which has caused it to shut down for safety.
Your boiler's internal computer is experiencing a configuration error, which prevents it from knowing how to safely operate your heating and hot water.
Your boiler's internal computer is experiencing a communication error, meaning it has forgotten its operating settings and cannot safely start up.
Your boiler's computer is experiencing an internal error, which has safely stopped the unit from running to prevent any unsafe conditions.
Your boiler is having trouble communicating internally, which is causing it to shut down for safety reasons.
Your boiler has detected a communication issue between its internal parts, meaning it has safely switched itself off to prevent further errors.
Your boiler has detected a communication error between its internal electronic parts, causing it to shut down for safety.
Your boiler has lost the chemical signal needed to release gas, so it has safely shut itself down to prevent any unsafe operation.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
Your boiler's temperature sensor is providing incorrect readings, so it has safely shut down to prevent overheating.
Your boiler has detected that the water inside the heating system has become too hot and has automatically shut down to prevent damage.
Your boiler is failing to detect the expected temperature rise after the flame ignites, which means it cannot safely heat your water or radiators.
Your boiler is trying to start but the flame is not catching, meaning you currently have no heating or hot water.
BoilerFaultCodes