Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4

Measurement:

Remove the plug-on connector on PCB 27 marked CON 2 gas valve 3 (violet wires).
Measure the resistance across the two violet wires on the connector.
Resistance should be greater than 3.5 Ohms.
Replace the plug after the test.