Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
DHW Tap OFF
Disconnect the X2 connector from the PCB
Disconnect the X2 connector from the PCB
Measurement:
Test between the Pink (7&8) wires to the DHW flow switch.
Measure the resistance between the two wires, resistance should read open circuit as the tap is not on.
Measure the resistance between the two wires, resistance should read open circuit as the tap is not on.
Isolate as per TOPs P4
and refit as necessary