Service Engine Soon light

I have a 2003 Maxima SE with approximately 69K miles. The "Service Engine Soon" light came on a couple of days ago and has remained on. No noticable difference in performance and I'm the kind of driver that notices everything. Any thoughts?

Could be O2 or Knock sensor. Take it to your local Auto Zone and have them pull the codes. They will do it for free. Once you do that check out maxima.org and search your pxxxx code given and you will get a lot closer.

Good luck.

Do just as Bezerk said. Or you can buy your own code reader for around $50, pull the code u'rself. Its as handy as a screwdriver these days. The code scanner will give you some idea of what the P0XXXX number means. I also use it to clear codes just before state emissions.

Thanks for the help.

I went to a local Checker Auto Parts store (Auto Zone was too far away) and asked if they could pull the codes. They let me use their device. The code was P0455 "Evaporative Emission System Leak Detected (gross leak/no flow)". The counter rep told me this was a gas cap problem. I used their device to clear the code and put my gas cap back on. The light came back on. Cleared the code again and put a new gas cap on. The light has not come back on since! Now I'm puzzled as to what happened to my old gas cap. It doesn't show any cracks and has alway been attached to the filler door. Bad seal? Anyway, $8.00 (U.S.) solved the problem. Thanks again.