Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect 5-pin connector from pcb

Measurement:

Measure for continuity between the disconnected connector and the 5-pin terminal block within the combustion box.
The resistance should conform to the table below:
LeadsResistance
Blue - BlueContinuity
(zero resistance)
Brown - Brown Continuity
(zero resistance)