Set Appliance State:

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

Observation:

Allow appliance to reach reasonable operating temperature (at least 60°C)
Remove CH demand.
Does the pump continue to run for at least 1 minute?
(Appliance is set to overrun for 2 minutes by default, it can be adjusted from 1 to 99 minutes by accessing P22, click here for instructions)