Set Appliance State:

Mains Power Off
CH Demand
Mode Switch in HIGH position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the boiler to operate and reach a high operational temperature.
Switch off the Room Thermostat/External Controls.
Does the Pump continue to run until the boiler is cooled down sufficiently?
Note: It may be necessary to reduce the heating load by turning off some radiators. This will shorten time required for this test.
If no Room Stat/External Controls are fitted:
Isolate Mains Power to appliance as per TOP's P4

Remove the Link (White wire) between HW and ON terminals.
WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure
Mains Power On
Repeat the test.