Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Selector switch to hot water
DHW temperature selector to maximum
Attach a pressure gauge to the gas inlet pressure test point
Gas On
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow ignition sequence to commence and sparking to occur.
Does the pressure gauge show an inlet pressure of at least 18 mbar throughout the sequence?
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.