Set Appliance State:

Gas Off
Set Multimeter to Resistance Set meter to measure resistance
CH Demand
Isolate Mains Power to appliance as per TOPs P4
Selector Switch to winter position
Turn Boiler Thermostat fully clockwise
Remove plug J11
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure resistance across black wires of plug J11.
Note:
Do not take measurement on PCB.