Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4

Observation:

Visually inspect the flow and return temperature probes.
Ensure the flow probe (red leads) is clipped securely to the primary heat exchanger pipe top left of appliance in the location as shown in the image.
Ensure the return probe (blue leads) is clipped securely to the primary heat exchanger pipe to the rear of the appliance behind the fan in the location as shown in the image.