Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect lead marked "HT" from the PCB
Remove burner assembly
Remove injector assembly

Measurement:

Check electrode is in good overall condition:
  • Ceramic uncracked
  • Electrode not warped or distorted
  • Gap between electrode and pilot assembly should be 3-5mm
    Check for continuity (zero resistance)
    between the tip of the electrode to the end of the lead.
    Inspect the harness insulation is in good condition throughout
    and there are no signs of shorting against the boiler chassis.
    Note:
    Ensure gasket is in good condition
    and fitted correctly on reassembly.