Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
CH Demand
Boiler Switch in ON position
Central Heating switch in Constant position
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Is there mains voltage between L and N terminals on water pump connector?
Note:
Boiler may go to lockout, switch OFF power and press reset switch to cancel lockout.