Set Appliance State:

Gas Off
Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Unplug connector CN1

Measurement:

Measure resistance across connection 1 (Purple wire) and connection 2 (Orange wire).
This should be approximately 50 Ohms.
Replace connector CN1.
Note:
This test should be carried out on the disconnected connector not on the PCB.