11 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Greenstar 28i Junior
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 an internal error preventing it from starting up, most likely due to an issue with the electrical circuit board or a blocked flue.
Your boiler has detected a critical internal error that is preventing it from starting safely.
Your boiler has detected a safety concern or internal fault and has automatically shut down to protect itself, requiring you to manually restart it.
Your boiler is struggling to clear exhaust gases safely, so it has stopped working to prevent any risk to your home.
Your boiler has automatically turned itself off because it is getting too hot, likely due to a flow issue within your heating system.
Your boiler has switched itself off because the water inside it has become dangerously hot.
Your boiler is struggling to detect gas or initiate the heating process, which may be caused by a loose internal connection or an issue with your gas supply.
Your boiler has failed to start the flame needed to heat your home and has automatically locked itself for safety to prevent a gas buildup.
Your boiler is failing to ignite the flame it needs to heat your water, so it has safely shut itself down to prevent a build-up of unburnt gas.
Your boiler has switched itself off because it has detected an unsafe rise in internal temperature and needs to cool down before it can restart.
Your boiler has detected that the internal water temperature has become dangerously high and is running the pump constantly to try and cool itself down.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes