Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
Gain access to PCB (use Insulation Mat as required)
Remove the flame sense lead from connection marked
X15 on the PCB
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure voltage across the exposed terminal (X15) on the PCB and an adjacent earth terminal.
Expect approximately 230 V AC.