Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect the leads from the spark electrode and carefully remove the electrode assembly from the combustion box door

Measurement:

Thoroughly inspect the electrodes as below:
  • Ceramics not cracked.
  • Electrodes not warped or distorted.
  • No build-up of contamination on electrodes.
  • Detection electrode approx. 18mm in length (not burnt down).
  • Spark gap is 3.5mm +/- 0.5mm.
  • Connectors to ignition lead and rectification harness are a tight fit.
    Measure the resistance between the tip of each electrode and its corresponding wire.
    Expect continuity / zero resistance.
    Note:
    Before reassembly check the integrity of all disturbed gaskets and seals and replace as necessary.