Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect plug marked CON14 at the PCB
Measurement:
Test 1:
Measure the resistance between the blue and brown
wires at the disconnected plug.
Resistance should be between 1k - 1.3kΩ.
Test 2:
Measure the resistance at black wire at the
disconnected plug to a suitable earth point.
Resistance should be greater than 1MΩ (or O.L).
Note:
Gas valve plug may look different (no blank pins).
It is in the same location and resistances do not change.
Measure the resistance between the blue and brown
wires at the disconnected plug.
Resistance should be between 1k - 1.3kΩ.
Test 2:
Measure the resistance at black wire at the
disconnected plug to a suitable earth point.
Resistance should be greater than 1MΩ (or O.L).
Note:
Gas valve plug may look different (no blank pins).
It is in the same location and resistances do not change.
Isolate as per TOPs P4
and refit as necessary