Set Appliance State:

On/Off Switch OFF
Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Disconnect gas valve electrical connector plug
(held by one centre screw) from gas valve

Measurement:

Test 1:
Measure resistance across the
top and bottom pins on the gas valve.
Expected resistance approximately 4250 Ohms.
Test 2:
Measure the resistance from the top pin on the gas valve to a suitable earth point.
Expected resistance greater than 1M Ohm.