7 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: 28i Junior
Pick the one you have. The fault codes, GC numbers and manual differ by type.
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 →
Tap any card for details
Your boiler has detected an internal fault preventing it from lighting, most likely caused by a failed safety sensor or a malfunction in the ignition sequence.
Your boiler has detected an internal safety lockout error, causing it to stop operating to prevent potential damage or overheating.
Your boiler has detected a safety concern or internal fault and has automatically shut down to protect itself, requiring you to attempt a manual reset.
Your boiler has automatically turned itself off because the water inside it is getting too hot, likely due to a circulation problem.
Your boiler is failing to light the gas burner because it is not receiving the correct signal to start the heating process.
Your boiler is failing to light the flame properly, so it has purposefully shut down to prevent gas from building up inside.
Your boiler has sensed that it is dangerously overheating and is running the pump constantly to try and cool itself down.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes