Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Turn Hot Water Tap On
Disconnect the 4 way plug at the back left of the PCB
Measurement:
Measure resistance between the connection marked 26 on the disconnected 4 way plug and connection 14 (located second from the left on the 6 way plug at the back right of the PCB).
Isolate as per TOPs P4
and refit as necessary