Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
DHW Temperature Selector set to MAX
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset appliance as necessary.
Observe through boiler sight glass as the boiler
goes through its ignition sequence.
Shortly after the fan starts to run is sparking present at the ignition electrodes and does the burner ignite smoothly and establish?