Set Appliance State:
Set Multimeter to Resistance 
Isolate Mains Power to appliance as per TOPs P4
Remove ignition electrode from its housing and disconnect from PCB
Remove ignition electrode from its housing and disconnect from PCB
Measurement:
Thoroughly check the electrode and lead for signs of damage, cracked ceramic and cleanliness.
Measure the resistance between the end of lead on spade connector and tip of electrode.
Expect continuity / zero resistance.
Note:
Before reassembly check the integrity of all disturbed gaskets and seals and replace as necessary.
Measure the resistance between the end of lead on spade connector and tip of electrode.
Expect continuity / zero resistance.
Note:
Before reassembly check the integrity of all disturbed gaskets and seals and replace as necessary.
Isolate as per TOPs P4
and refit as necessary