Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
To expose the controls PCB, Lift up the main PCB
Remove ribbon cable from controls PCB

Measurement:

Measure the resistance across the center and left pins of the DHW potentiometer.
The resistance will alter as the potentiometer is turned and should conform approximately to the table below:
PositionResistance in Ohms
MIN3.5 Ohms
MID 3.8k
MAX4.2k
PREHEAT3.6k