Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Disconnect wires marked "WEATHER COMPENSATION"
at top right of PCB housing and make safe
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Does the boiler now operate correctly?
Note:
Full outdoor sensor instruction manual available HERE.