Set Appliance State:

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

Observation:

Allow the burner to ignite and appliance to run in central heating mode, this can take a further 2 minutes from when the demand was recognised on the previous test.
(d1 or d2 may be displayed during this time these are not fault codes)
Monitor the system pressure.
Is the heating operating satisfactorily ?