Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove the burner assembly from the boiler
Measurement:
Inspect the flame detection electrode for general condition.
Make sure the gap to the burner is 7.5mm (+/- 1mm)
Check for continuity (zero resistance) between the ends of the flame detection electrode.
Make sure the gap to the burner is 7.5mm (+/- 1mm)
Check for continuity (zero resistance) between the ends of the flame detection electrode.
Isolate as per TOPs P4
and refit as necessary