I have a 2004 Chevy Monte Carlo LS. It has 138000 miles on it. The Check the engine light just came on. What could be the problem?
Most auto parts stores (Auto Zone, Advance, Pep Boys, etc) will tell you for free. They hook up a computer device which gives codes that say “P1234” for example. Post them back here (the codes, not the english explanations) and the experts can help you. I am no expert but have learned a lot from others on this site.
“The Check the engine light just came on. What could be the problem?”
That is the automotive equivalent of saying to your doctor, “I have a pain in my body. What is wrong with me?”
Just as the possibilities for a human diagnosis are almost endless, given the lack of specificity, the possibilities for an automotive diagnosis cover perhaps several hundred possibilities.
As was already suggested, the first step is to get the car’s OBD system scanned for stored trouble codes. Then, if you come back to this thread and post the codes (in the format of P0123), we can likely give you some specific advice, based on the code(s).
The CEL is an early warning system. There are many possible reasons the light has come on. Too many to list here. If you have a mechanic with whom you deal on a regular basis, take the car to him or her.
You can also go to just about any auto parts store and they will scan the computer for you. Then you’ll have a trouble code, which may or may not mean much to you.
Trouble codes DO NOT say, “replace component x,” or anything similar. All they do is give your mechanic a place to start looking and testing.
If you don’t have an independent mechanic with whom you deal on a regular basis, now is the time to find one.
That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.
I think it would be a good thing if codes were displayed in a format that made further inital work to find out at least what they mean discovered. Was the decision to only display the fault in code form driven by the technology of that day or was this an effort to keep mainly emmission related codes out of the hands of people who might not be trained?
the problem could be anything from simply tightening up your gas cap to severe engine damage coming your way soon if you don’t get it to a shop and get it fixed. The only way to find out isn’t here, it’s at a mechanic’s shop.
edit: I agree with oldschool’s post. With more and more electronic displays for odometer and such, it shouldn’t be too difficult for car makers to have the code come up briefly every so often so one could find out what’s wrong. Car gets a code, display comes up, owner calls the shop with the code, shop says “oh that’s just a code for a loose gas cap, try tightening it up, then do X to get the light to go out if that’s all it really was.” Or, hell, for those vehicles that have the multi-info display in their car, the code could pop up with a description on the MID with possible solutions to try out.