On my 01 xj sport with the 4.0, the check engine light is on. I went up to auto zone so they could check it. The auto zone guy said it turned out to be an emissions leak. He said it could be a vacuum leak, a solenoid, gas cap being loose or something else. Has anyone had this problem? The jeep drives perfectly fine. I wouldnt be that worried about it, but I'm looking to sell it soon. I would rather sell it without that light being on because I think it would be easier to get rid of. I'm a rookie mechanic so I have no idea where the selenoids or vacuum lines are located. Any info on what and where to check would be appreciated.

 

disconect the batter for 30 seconds and see if it turns back on. Might have just been a loose gas cap.

 

The gas cap does NOT look stock, and it doesn't seem very tight, so it's quite possible. The only reason I don't think that it's the culprit is because I have had this jeep for months now, and this gas cap has been on the whole time with no check engine light. I will disconnect the battery and see what happens.

 

I didn't even have to disconnect the battery. I got back out to my truck after typing that last reply and after 3 weeks of the check engine light being on, it miraculously turned off on it's own completely random.

 

Very possibly the seal on the gas cap.

If it comes back, please post the exact code. With OBD, the devil is definitely in the details.

 

Will do, thanks