Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Remove ignition electrode from its housing

Measurement:

Thoroughly check the electrode and lead for signs of damage, cracked ceramic, shorting and cleanliness.
Measure the resistance between the end of lead on spade connector, and tip of electrode.
Expect continuity / zero resistance.