It stored a defined Diagnostic Trouble Code (DTC) in its computer memory and evoked an amber dashboard light. The ability to self-diagnose was often a confounding aspect of the GM system.

If you're a personal user, knowing how to read and interpret OBD codes is a trick that's well worth having up your sleeve for those times when the Check Engine light in your car suddenly comes on ...

Q:My ABS light came on last week on my 2006 F-150. The auto parts store read the code and said it was the rear center ABS sensor. I bought one, replaced it, and cleared the codes, but the light ...