Set Appliance State:

Mains Power Off
CH Demand
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset lockout as necessary.
Allow fan to run and ignition sequence to commence.
Does burner ignite and establish?
(The flame can be seen through the viewing window on the front of the inner panel)
CLICK HERE TO INVESTIGATE INTERMITTENT IGNITION LOCKOUT
This will take you through a large range of tests to check as many components as possible that may cause intermittent ignition lockout, this should only be selected if the appliance appears to be working satisfactorily at the time of your visit and it has been reported that the appliance is experiencing intermittent ignition lockout.