Long story short I've had my 2000 mustang since November and I was just cleaning some dust out of my instrument cluster and noticed the cluster was missing the bulb for the check engine light. I replaced the missing bulb and low and behold I now have a lit CEL!!! My car is running great and doesn't have any problems that I know of. So my question is what can trigger the CEL in an otherwise perfectly running mustang.

 

just go to autozone, and have them plug it in, and see what code it throws.. its free

 

oh man it's probably just a simple sensor, on the 3.8 the likely culprit is the dpfe sensor ($45 from advance auto) or quite possibly a dirty MAF this will probably shoot a running lean or running rich code. anyways find the code post it and we can help you diagnose. to find it do what the above poster said take it to auto zone and they will read it for free. good luck!

 

Thanks for the input... I'm going to take it to autozone tonight after work. I recently cleaned the MAF and intake so I doubt that threw the code. This dpfe sensor when it goes bad does it cause any symptoms or just throw a code?

 

it pretty much just throws a code in my experience, maybe over a long period of time it could cause symptoms but i didn't have any when mine went bad

 

DPFE doesn't cause any issues just a code. You need to get the code first then figure out what it means. You can't say that it is a DPFE if you don't know what the code actually is.[/align]What are you going to tell someone that has a Bank 1 long term fuel trim code? To throw an 02 in it? Of course you will. Then the guy just went out and spend hard earned money on an 02 when he needs a $10 fuel filter. Get a friggin clue kids![/align]

 

i didn't tell him to replace a part, i listed common failures on the 3.8L engine. the dpfe sensor was given an extended warranty because they have a tendency to fail so that is why i told him that is a likely problem. don't call me a kid, read the actual post dbag.

 

Hopefully you don't have the same problem I did, my 99 threw a CEL on the way home from the dealership and it was a bad AIR pump, a Ford dealer charged $800 to fix it. [:@] (The dealership I bought it from said that was not covered under their warranty and they "forgot" to tell me about it because the dealership was in OH and they have no emissions, whereas I live in PA and I do have emissions so I need it to pass inspection here whereas they didn't need it to pass inspection there.) The car drove perfectly fine with the light on.

My LS1 Camaro used to have chronic CEL problems, it was a dirty MAF, I cleaned it a few times but it would still throw the code because the MAF was really sensitive and didn't like the cleaner I was using. That's probably not your problem if you've got no driveability issues though because the Camaro would run rough when the code was being thrown, since the MAF wasn't metering the air properly it was throwing off the tune.

 

Oh yeah, and on a related note the next day I bought an OBDII scanner, I will never buy another car without scanning it first again.

 

I used to be a sales manager at Autozone... Going there is your best bet to have it scanned, because its free. They have a notebook with possible causes of the code that comes up. The most common code I saw in this siuation is Oxygen sensors. They will turn the light on and the car is still fine. Sometimes with bad O2 sensors, you will get a decrease in gas mileage. And there may be nothing wrong--- If something triggered the light, such as a loose gas cap at one time, the light doesn't always turn itself off.... So say you have a bad O2 sensor so you replace it... The light is still on even though the prob is fixed... You have to turn it off with an OBDII Scanner. Hope this helps!