Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove the ignition harness from the PCB
and the spark electrodes

Measurement:

Measure the resistance of ignition harness from the PCB connector to the spark electrode connections.
Expect approximately 2.2kohms
Also inspect the harness visually.
Note:
Check both ignition leads in the harness.