Your boiler has stopped working because it cannot confirm that the flame is properly lit, causing the system to shut down for safety.

Error with the flame monitoring

What causes this fault?

This fault occurs when the boiler's internal computer is unable to detect a steady flame during the ignition process or while the burner is running. It is often caused by a dirty or damaged sensing probe that can no longer 'see' the heat, or a communication failure in the wiring that carries this signal to the control board.