Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove the plug from underneath the flow sensor and from X2 on the PCB

Measurement:

Check for continuity (zero resistance)
between the ends of each of the three
wires for the flow sensor harness
(Pins 10, 11 and 14 on connector X2)
Inspect the harness for good overall condition