Your boiler is starting up briefly but then failing to detect a flame, causing it to shut down for safety.

Burner extinguishes after 10 seconds. Go to section ‘I’.

What causes this fault?

This fault occurs when the boiler successfully lights the burner but fails to recognise that the flame is present, leading it to shut down for safety. The most common reason is a worn-out sensor electrode that can no longer send a signal to the control board, or a fault within the electronic circuitry itself. Essentially, the boiler is 'blind' to its own fire and turns the gas off to prevent an unsafe build-up.