The sensor reacts to shock. If the car is off you will not have any problems with the air bags going off. If the car is on don't hit the sensor with a hammer.

I thought that the sensors were grounded through bolt that holds them to the steel structure behind the grill. You need to make sure it is clean and has a good connection.

1998 Contour SVT Black w/ Blue interior Torsen LSD updated shiftforks Lightened Flywheel, HD Drivelines Optimized Thottle Body 2003 3.0L engine upgrade (Soon to be)