Set Appliance State:

Gas Off
Set Multimeter to AC Volts Set meter to measure AC Volts
CH Demand
Isolate Mains Power to appliance as per TOPs P4
Gain access to pcb (use isolation Mat as required)
Boiler On/Off Switch On
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Reset lockout as necessary.
Allow ignition sequence to commence.
Measure the voltage at connector CN1 connection 8 (brown wire) on the ignition PCB to a suitable neutral.
Approximately 8 seconds after the fan starts mains voltage should be present for 3 to 5 seconds. This should repeat 5 times before boiler locks out, with approximately 5 seconds between attempts.
Note:
To reset the boiler switch the boiler On/Off switch Off then back On.