Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Hinge down the PCB housing
Disconnect gas valve electrical connector plug from gas valve

Measurement:

Test 1:
Measure the resistance between the top and bottom pins on the gas valve.
Expected resistance approx. 4.1kOhms.
Test 2:
Measure the resistance between top pin and middle pins on the gas valve.
Expected resistance above 1 MOhm.