Your boiler is unable to light because the internal system that controls the gas flow has stopped working correctly.

Fault diagnosed related to gas valve 1 or 2, or specific solenoid in a double solenoid gas line.

What causes this fault?

This fault occurs when the boiler's computer detects that the safety valves responsible for letting gas into the burner are failing to open or close correctly. The most common reason is an electrical failure within the valve's internal coils or a communication error from the main control board, which prevents the boiler from lighting safely.