Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow boiler to run for DHW.
Does the boiler shut down & display (fault code) ALL 09?
Note:
If the boiler fault code changes from the original to a different fault code, then CLICK HERE.