I received a questionnaire card in the mail a few weeks ago from the NHTSA. Then just received this follow-up email from them today. I really don't want to drive my truck now.
Of the Ford F150 Trucks that I have inspected in the field, Lamp Fault Code (LFC) of 4-2 is quite common. It indicates a “Restraint System – Impact Sensor Fault.” This could be a problem with the sensor, wiring, etc.
Our investigation is on 2004-2006 Ford F150 Trucks and centers around the remote possibility of a driver air bag inadvertent deployment.
You can find information on the investigation at:
http://www-odi.nhtsa.dot.gov/cars/problems/defect/defectsearch.cfm
Then enter <EA10001> in the NHTSA Action Number Box.
The information reads in part:
“FORD REPORTS THAT INADVERTENT AIRBAG DEPLOYMENTS ARE MOST LIKELY CAUSED BY THE AIRBAG HORN MOUNTING PLATE'S SHARP METAL EDGE THAT EVENTUALLY CAN CHAFE/CUT THE AIRBAG CLOCK SPRING JUMPER WIRE LEADING TO A SHORT-TO-GROUND CONDITION.”
Other documents can be looked up as well.