Set Appliance State:

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

Observation:

Allow the burner to ignite and boiler 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)
Is the heating operating satisfactorily?