Your boiler has detected an internal electrical problem with the component that controls the gas supply, meaning it has shut itself down to ensure your safety.

Gas valve relay faulty

What causes this fault?

This fault occurs when the boiler's control system loses communication with the fan or detects that it isn't spinning at the required speed. The most common reasons are a mechanical failure of the fan motor itself, loose internal wiring, or a fault on the main circuit board failing to send power to the unit.