Questions and Answers

Pontiac Grand Prix Check Engine Q. I have a 1989 Pontiac Grand Prix 3.1 liter, automatic transmission and when I'm driving my check engine light comes on and off when it feels like it. But the funny thing is the car runs just fine, no miss in engine, no nothing, all the sensors are plugged in, so maybe you can help me???? Thank you, Cory

A. A scanner will help here. Everytime that light comes on a diagnostic trouble code stores in the PCM. A scanner is the only way to read these codes unless you jumper A-B at the data link connector under the dash. This will flash the check engine light and read out the DTC's. Then you need to know what the code means.

Diagnostic Trouble Codes