Your boiler has detected an internal communication error with the internal fan, which means it will stop working to ensure your safety.

Electrical fan control (control unit) faulty

What causes this fault?

This fault occurs when the boiler's control system loses the ability to precisely adjust the amount of gas entering the burner. The most common cause is a failure in the electrical coil that moves the internal gas valve, meaning the boiler can no longer maintain a safe and steady flame to heat your home.