Your boiler has stopped working because the internal fan, which safely clears waste gases, is not spinning or communicating with the main control board.

No signal from fan

What causes this fault?

This fault occurs when the boiler's control board sends a command for the fan to start, but detects that the fan isn't spinning at the required speed. The most common reason is the fan motor itself failing after years of use, though it can also be caused by loose electrical connections or a fault on the main circuit board. Because the fan is responsible for safely removing exhaust gases, the boiler will refuse to ignite as a safety precaution.