Anyone who has driven a car for years has had that panicked feeling when the "check engine" light came on.  Is the car going to burst into flames?  Am I permanently damaging the engine by continuing to drive?  Should I pull over and call AAA or just limp home?I've been in that position several times, and then I had to blindly trust the repair guy at the shop when he brought me me the estimate with dollar signs in his eyes.  They charge me $80 for using a diagnostic machine like this one, plus parts and labor for whatever they say is causing the problem.  Even with a shop I mostly trust, I always feel like they push for repairs I don't really need.  I don't like feeling taken advantage of, or having to trust that I really need a new widget for $800.  This fault code reader will save me lots of money by letting ME decide whether the repair needs to be done now or later.This meter works on cars built after 1996, most of which are OBD-II compliant (they use the same type of plug for the meters, and the coding system for errors).  It plugs into an outlet that's found under the dash on the driver's side in most vehicles.  Mine was hanging right there in plain view when I looked under the dash.  You plug the meter in, then turn the ignition to "on" but don't start it.  The meter will do the diagnostic and then give you whatever codes it finds.  You can look in the meter's user's manual or online to see what the codes mean.  It's really that simple.On the meter's package, I read something I wouldn't have thought of myself.  If you're thinking of buying a used car, you can use this meter to check the soundness of the engine.  It will show you any hidden engine issues via the stored codes in the car's computer.  Brilliant!I don't have an error code to diagnose right now, but I did plug the meter in on my car so I'd be able to write a knowledgeable review.  I will love going to the repair shop next time and being able to tell THEM what the error code is.  If I know the code has nothing to do with an $800 widget, I won't be taken advantage of.I received a complimentary DB Power Engine Diagnostic Fault Code Reader for testing and review purposes.