Set Appliance State:

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

Observation:

Allow self-check to complete and the boiler to ignite and run on central heating operation.
Is the heating operating satisfactorily and system pressure remain stable?
Note:
If fault code overheat occurs during CH operation CLICK HERE