Your boiler is unable to safely control the flow of gas needed to stay lit, so it has shut down to avoid a potential hazard.

The diagnostics will indicate which gas valve (1 or 2) or solenoid of the double solenoid is at fault

What causes this fault?

This fault occurs when the boiler's internal computer detects that the gas valve is failing to open or close correctly during the ignition process. The most common reasons are a mechanical failure within the valve assembly, a burnt-out electrical coil, or a loose connection in the wiring harness that prevents the valve from receiving power.