Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Remove the plug from the gas valve

Measurement:

Measure the resistance across the terminals of the gas valve.
Resistances should be approximately as in the table below:
PinsResistance in kohms
1 - 21.8
4 - 5 1.8