16 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 detected a critical internal error with its fan or electronic memory and has shut down for safety.
Your boiler has been left in a manual testing mode after a recent service or inspection, which is preventing it from running normally.
Your boiler has been left in a manual testing mode after a recent service or inspection, which is preventing it from running normally.
Your boiler is having trouble measuring the temperature of your hot water, which usually means it cannot heat it safely or effectively.
Your boiler's internal computer has lost its connection with the main control board, meaning the system cannot communicate correctly to heat your home.
Your boiler's internal computer memory chip is loose or missing, meaning it cannot identify which model it is supposed to be.
Your boiler's fan is spinning faster than it should, which means the system has safely shut down to prevent any damage.
Your boiler has lost track of the temperature of the water flowing through it because an internal sensor is broken.
Your boiler has got too hot and has automatically shut down for safety to prevent damage.
Your boiler has failed to light, which most likely means the gas supply is interrupted or there is a blockage preventing the burner from starting.
Your boiler's internal computer has encountered a glitch or a hardware failure, preventing it from running properly.
Your boiler thinks it can still see a flame inside after it has been told to turn off, which is a safety conflict.
Your boiler thinks a flame is still present even though the gas should have been turned off, which is a safety concern that prevents it from running.
Your boiler is temporarily confused because the reset button was held down for too long or pressed when it wasn't needed.
Your boiler is receiving power and trying to work, but it has failed to start the burner to provide heat or hot water.
Your boiler appears to have no electrical power at all, meaning the screen and lights are completely blank and it will not provide any heating or hot water.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes