Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Set Boiler Control Thermostat to MAX position
Attach pressure gauge to burner pressure test point
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Reset boiler as necessary.
Allow ignition sequence to commence and sparking to occur.
Does the pressure gauge show a burner pressure of approximately 4.5mb then rise to its set burner pressure between 10.4mb and 13.6mb?
Note:
When pressure gauge is removed pressure test point should be tightened & checked for gas soundness.