Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Disconnect connector X3 from the Main PCB

Measurement:

Measure the resistance across connection 4 (Violet wire) and connection 5 (Red wire) at disconnected plug.
Note:
Measurement taken at disconnected plug not PCB.