The following is from the Ford TSP:

45=LH Primary Crash Sensor Not Mounted to Vehicle Properly

Normal Operation

The air bag diagnostic monitor measures the resistance between Pin C2-21, Circuit 9 (BR) and Pin C1-3, Circuit 91 (BK/R), diagnostic monitor reference ground. If the air bag diagnostic monitor measures a difference of more than 2.0 ohms between Pin C2-21 and Pin C1-3, it will flash Code 45.

Note that Circuit 9 (BR) is grounded to the side of the LH primary crash front air bag sensor case and the case is grounded to the vehicle at its mounting point.


Possible Causes

High resistance on Pin C2-21, Circuit 9 (BR) to ground can be caused by:

(1) A poor connection due to loose mounting or dirt at the LH primary crash front air bag sensor and bracket mounting location.

(2) An open or damaged wire Circuit 9 (BR) from Pin C2-21 of the air bag diagnostic monitor harness connector to LH primary crash front air bag sensor.

(3) An open circuit inside LH primary crash front air bag sensor.

96 Contour SE Duratec V6 24-valve 2.5L ATX 108,000 mi. Replaced: crankshaft w/ DMD, EGR valve (clogged), EVR, DPFE, PCV valve, evap emissions hose & tube (cracked), window regulator (broken), LH & RH PCV tubes, UIM gasket (leak), ignition coil