Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Remove knob from CH Potentiometer on Main PCB

Measurement:

Measure across left and right terminals of DHW Burner Pressure Potentiometer.
Resistance should be approximately 4.5 kOhms.
Replace knob.
Note: Do Not Adjust this Potentiometer.