Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Central Heating Thermostat to Maximum Position
DHW Thermostat to Minimum Position
Refit integral programmer
Unplug the 4 wire terminal block for the TR2 connector
from the internal programmer and make safe
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Does the boiler now fire with the TR2 connections removed?
Note:
If boiler is not fitted with a TR2 stat (no wires fitted
to terminal block) then select "boiler does not fire".