Good question! You are not alone when looking for the answer to this question. This light is a computer generated light telling you that your car needs to be checked out. All modern vehicles have a computer (aka ECM= Electronic Control Module). The ECM controls the operation of the vehicle, the engine and transmission. Its main purpose of this is to keep the engine running at top efficiency with the lowest possible emissions.
Some service manuals contain a list of possible codes and describes what each code means and what needs to be tested. The code itself doesn't tell exactly what component is defective - it only indicates where to look, and what sensor is out of normal range. Your technician will be able to retrieve a code by using a scan tool to diagnose the problem.
You can also go to any Auto Zone and get a free code reading as well.
Thanks for asking such a great question!
〉 Answered on May 5th, 2010 by Audra Fordin, Owner at Great Bear Auto Shop
The service engine light indicates that the vehicle is not running correctly or as efficiently as it should. There are numerous issues that can make the service light illuminate. It could be as simple as a loose or leaking gas cap, or it could be something much more complicated. I suggest you have your vehicle checked out by a qualified technician that can properly diagnose the problem and suggest a solution.
〉 Answered on May 5th, 2010 by Suzanne Grego, Technician at City of Philadelphia Fleet Management