I have two Chevy Impalas (2000 Impala LS, 3.8 V-6, and 2002 Impala, 3.4 V-6).
I had a similar problem with the 2000 Impala.
I was driving home from work at about 65 MPH in the fast lane of the freeway when the engine just quit. The message center came on red with a "BATTERY" image. I miracuously managed to make my way to the right shoulder. While sitting there trying to decide what was going to be my next move, I decided to try to start the car. (About 5 minutes had passed). To my surprise, it started and I continued on my way home without any problem.
I had about 10 or 12 of the same type incident in the next 4 months, usually after 20 to 30 minutes of operation. After it happened once in a day, it wouldn't happen again until it had set overnight. I got to where I would just let it rest for a while and then restart it and go on my way.
I had been told at a Chevrolet Dealer's repair shop that "Unless it happens while we are witnessing it, then there must be nothing wrong." I must note here that the car's computer does not see this as a problem. I sees it as the ignition switch being turned to the "OFF" position. There is no problem code generated for a code reader to read.
Anyway, I found a mechanic who was willing to work with it for awhile. After about a week, during which he told me he thought my car was possessed, he finally changed the Crankshaft Position Sensor and the problem was fixed. No problems have occurred since and it has been over 3 years.
I had the mechanic give me the part that he replaced and I have done some investigation on the probable cause of the problem. There was no obvious damage. The only thing I found, that I thought was odd, was a buildup of metallic particles in one of the grooves that straddles the Crank pulley. That part of the sensor is obviously magnetic. I don't know, but I suspect that if this metallic material were removed, it might fix the problem.
I do know that replacing it will definitely fix it.
Good luck to you.
Friday, July 3rd, 2009 AT 5:41 PM