Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector CN2 from the PCB & electrical connector at gas valve

Measurement:

Measure the resistance (continuity) across the gas valve harness leads.
Connections are;
CN2 pins 5 & 6 to the corresponding connection at the gas valve connector, see table.
Expected resistance is continuity (zero resistance) across each wire of the harness.