Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove the red leads from the modulation gas valve
Measurement:
Do NOT disconnect the connector from the PCB.
Measure the resistance across the
disconnected spade terminals from
the gas valve at pins 6 and 8 (red wires)
on the 24 way connection block (X2) on the PCB.
Measure the resistance across the
disconnected spade terminals from
the gas valve at pins 6 and 8 (red wires)
on the 24 way connection block (X2) on the PCB.
Isolate as per TOPs P4
and refit as necessary