Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove plug from air pressure sensor and remove plug from PCB on right hand side marked X15

Measurement:


Check the continuity and general condition of each of the leads in the harness.
Checking each lead in turn from air pressure sensor plug to PCB plug:
Does each individual lead show continuity?
Expected reading short circuit / zero resistance.