Your boiler is struggling to maintain a steady flame, causing it to shut down for safety reasons to prevent unburnt gas from building up.

Fault:Unstableflamesignal

What causes this fault?

This fault occurs when the boiler's control system detects that the flame is flickering or dropping out during operation. It is often caused by a worn sensing probe that can no longer 'see' the flame effectively, or a gas valve that isn't providing a steady enough flow of fuel to keep the burner alight.