Set Appliance State:

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

Observation:

With the fault code displayed does the appliance reset?
Press and hold the reset button for 5 seconds.
Please choose from one of the options below:
Boiler resets - Retest appliance
Boiler Resets but returns to same fault code