Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
CH Demand
Disconnect leads from spark generator and position on the edge of the housing as shown in the picture
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset boiler if it is in lockout.
Shortly after the fan runs can sparking be seen between the spark generator and the disconnected leads?