After I changed the fuel filter of my Bonneville 99 SSEi, days after the Check Engine light came on and it'* been 3 days on, I have no idea what it could be, cuz the car runs good. I was wondering a emissions sensor, or any type of sensor. Now the book in the glove box says it could also be front wheels, I think it also carries sensors.
Now before I changed the gas filter, a while back this light was on for while after engine start and it will turn off. But this time is on all the time when I start the car.
I would like to know all the reasons why, when this light comes on. I'm at 86 thousand miles.

Thank you, I love this website.

First of all make sure your gas cap is properly tight; the on-board diagnostics will detect if it isn't, and give you the warning light for that, so doublecheck that right now.

An auto parts store such as Auto Zone will usually get the stored error codes out of your computer for free. For the '99 Bonneville you need certain diagnostic tools to do that, which they have and you don't. But after that, we can tell you what to do based on what codes are in there.

At 86 thousand miles you're due for an oxygen sensor if nothing else, but don't replace _anything_ until you have those codes read out so you know what the car is complaining about.

I'll get to it asap. Thanx for the respond, but how do I get a hold of the diognstics that they have? Could I by those diognostics tools??

Thank you again...

Yes, although they are typically a couple hundred dollars or more, which is why AutoZone offers the readouts as a free service. If you did buy the diagnostic tools, they would enable you to get error codes from many cars, not just your own, but realistically they're in the area of professional tools, not something you'd need for yourself.

I mean, it'* sort of like buying your own air-conditioning evacuation and recharge equipment, or other specialty equipment: you _could_ do it (assuming it'* something you don't need special certification for), but it wouldn't pay for itself for a long, long time if you're not charging others for your services using it.

AutoZone and similar outfits offer the service for free because you're likely to be buying replacement parts or service from them as a result. Chances are that most people who come to them to get a Check Engine warning diagnosed will find that it'* something more than a loose gas cap.