Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector CN14 from the PCB
Disconnect the connector from the flow meter

Measurement:

Measure the resistance between each of the wires on
the flow meter harness.
Expect continuity / zero resistance on each of the wires.
Also visually inspect the condition of the harness.