Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector from pressure sensor (behind siphon, unlock for access)

Measurement:

Measure for continuity (zero resistance) on each of the wires (yellow, black, and red) running from the pressure sensor connector to pins 5, 6, and 7 at LV2 on the PCB.
Inspect harness and connectors for good overall condition.
Is the harness satisfactory?