Your boiler has stopped working because its internal computer and burner system have detected a technical communication failure.

Burner blocked - Internal error

What causes this fault?

This fault occurs when the boiler's main control board loses the ability to communicate with the internal burner firing system. It is usually caused by a hardware failure within the electronic control unit (PCB) or a loose connection in the wiring harness that links these critical components. Because the computer cannot safely verify the burner's status, it shuts the system down to prevent an unsafe start-up.