Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
DHW Demand
Use Insulation mat as required
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow ignition sequence to commence.
Measure the voltage at the 2 way connector on the brown and blue wires at the spark generator.
During the sparking phase of ignition expect a voltage of approximately 200 - 240 Vac.
Note:
Reset as necessary until test is complete.