[THEFERMANATOR]

Originally Posted by Seacrets

Typically, the check engine light is set to come on after a certain mileage so you will take it to a dealer for an emissions checkout. There is probably nothing wrong with your Jeep.

That is not the case here, I can assure you. After 92 no chrysler product used a maintence required system on them, and OBDII I believe is mandated NOT to have one. Go to AUTOZONE, they'll check it for you for free. On a 99 you may still be able to get the codes by the old key switch on off on off on off on(some take 3 on's and some take 4) self diagnostic in 2 second intervals and on the last on leave it there. On a 99 the odometer should read out the CHRYSLER HEX code, if it does I got the book to tell you what they are(or you can look them up on line as well). I don't think a 99 TJ will have an LDP, so a loose gas cap is probably not it. If the JEEP is running well with just a check engine light(after a cracked manifold), then chances are that it will be a cat efficiency code or downstream O2 sensor performance code. Only way to know for certain is to get the codes and go from there. CHRYSLER's OBDII is normally pretty spot on, so codes are normally a pretty reliable diagnostic tool.