SES Light Just Came on

[hospitalbuilder]

My SES light in my 99 QX4 just came on this morning. I recently changed the oil, and from everything I can tell the engine is running smoothly. My gas mileage is actually up some over the past month or so (warmer weather? new fuel formula?), it is running at almost 19mgp, and had been at about 17 through the winter months.

Any guidance on what I should do? I did a search and saw that some have gone to Auto Zone and had a reading from the computer. Is that something I can do? What are the likely culprets and are they someting I can fix myself? Thanks

[Densetsu]

The likely culprit can be *anything*... though O2 sensors seem to be the most common cause for SES lights.

You can either go down to a garage and have the code read, or pick up a basic ODBII reader for around $50. I'd suggest the latter, since it's a great diagnostic tool for any vehicle '96 and later (and most 95's as well).

I'm not familiar with the retailers in the US, but eBay has plenty of them.

If it is an O2 sensor, then they're fairly simple to replace. A Hayes manual helps, or a service manual can be found here: http://www.phatg20.net/index.p...id=31