Set Appliance State:

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

Observation:

Reset appliance, press and hold the reset button until the chimney
sweep button led flashes rapidly, then release the reset button.
Does the boiler reset?
Note:
1. If after boiler reset the fault code changes from the original to a different fault code, then CLICK HERE.
2. If the fault code is a recurring issue, then it may be that the components previously tested have intermittent faults, check electrical connections, water ingress, replace and/or repair as required.