Set Appliance State:

Mode selector switch to Off/Reset position
Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance
as per TOP's P4

Disconnect the moulded plug from the gas valve

Measurement:

Measure the resistance across top pin and third pin down. Resistance should be approximately 6.7 kOhms.
Measure the resistance across top pin and bottom pin. Resistance should be approximately 7.6 kOhms.
Reconnect moulded plug after test.