Your boiler has detected an internal electronics failure that prevents it from safely controlling the gas supply, meaning it has shut down for safety.

Main PCB gas valve shutdown fault

What causes this fault?

This fault occurs when the boiler's main control board detects a safety timing issue or an electrical failure when trying to shut off the gas valve. It is typically caused by a malfunctioning circuit board that can no longer communicate correctly with the valve, or a valve that is physically sticking and failing to close when prompted.