Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Selector Switch to Hot Water and Heating
Remove the spark ignitor cap and place below
the ignitor against the heat exchanger as shown
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset appliance as necessary.
Allow self check to complete and ignition sequence to commence
DO NOT hold the ignitor
Watch for sparking from the ignitor lead to the heat exchanger case.
Note:
Ensure the electrode lead is placed close to the heat exchanger casing for sparking to occur.