I have a 2000 Grand Prix SE. Last yr it would randomly start, but then shut off after 5 seconds. It always resolved itself within a day or so. The check engine light was on, so I had it scanned and it came up as the crankshaft position sensor. My brother works on cars and was going to replace the part, but was having a hard time reaching it without disassembling many things, so we decided since it was running ok after leaving it overnight, we would just let it go.
Now a yr later, after no problems recently, it did it again. This time even after leaving it alone, it won't start. I had it towed and they said they pulled up code 1629, which is related to the anti-theft system and it would be 10 days and $500 to fix it. I am second guessing them because my security light has never stayed on, or blinked. It comes on with the other lights as I start the car, so I know its not burned out. I did some research about the code and found it could be related to the crankshaft sensor. They are pretty adamant that its the anti-theft system though. Is it possible to have this problem and this code be related to the anti-theft module with no security light being involved? Could this code be related to the crankshaft sensor? Would it behave this way if that were the problem? Please, any advice would be greatly appreciated...I am a struggling single mom and don't want to replace something for $500 if I don't have to. Thanks.