Your boiler is trying to start up but the internal fan is not spinning properly, preventing the heating from firing up.

Fan start-up error

What causes this fault?

This fault occurs when the boiler's control system sends a signal to the fan to begin spinning, but it fails to reach the required speed to safely start the ignition process. The most common reasons are a build-up of debris or moisture inside the fan casing, or a communication failure between the main control board and the fan motor.