Set Appliance State:

Set Multimeter to Continuity Set meter to measure Continuity
Isolate Mains Power to appliance as per TOPs P4
Remove the Spark Electrode lead assy and Electrode from the boiler

Measurement:

Remove the Spark Electrode lead assy and Electrode from the boiler.
Confirm Electrode lead and Electrode are in good condition.
Carry out a resistance check of the spark Electrode and lead.