Set Appliance State:

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

Measurement:

Test 1:
Measure the resistance across terminal marked EV1 (L/H side) and terminal marked COM (centre bottom).
Resistance should be approximately 870 ohms.
Test 2:
Measure the resistance across terminal marked EV2 (R/H side) and terminal marked COM (centre bottom).
Resistance should be approximately 870 ohms.
Test 3:
Measure the resistance across terminal marked COM (centre bottom) and gas valve earth (centre top).
Resistance should be greater than 1Mohm.