I have a 99 Jeep Cherokee. 4.0 straight 6. My check engine light came on. And when I put it in park it idles high like at 3k. When I turn it off and cut it back on its normal. It comes and goes. Anyone know what's causing this?

 

Need a trouble code to know where to look. High idle could be a dirty IAC or the TPS. Could be something else. Vacuum leak perhaps? Need the code. I use an Actron CP9670.

 

The purpose of the check engine light is to tell you that the computer has stored a trouble code. That code will tell you where to start looking for the problem. People on message boards cannot magically guess what code your car has recorded. You have to pull it out of the computer.

Almost all auto parts stores will read the code for you for free. Just drive it to Auto Zone, Advance Auto, O'Reilly, Pep Boys, etc. and tell a clerk you need a code read. He or she will go out to the parking lot with a code reader, pull the code and look it up in their computer to tell you what it is. Some of them will give you a printout with the information, but be prepared to WRITE DOWN THE CODE AND DESCRIPTION so you can remember what it is. Then post that information here, and members will be able to help point you in the right direction.

If you're going to have an old Jeep with OBDII, you should invest in your own code reader for those times when you may not be able to stumble down to the auto parts store. If you have a smart phone, you can get an OBDII bluetooth (Android) or wifi (Iphone) adapter from Amazon for $15 to $25. I have this one for Android, and it works fine. Then you will need an app to read the codes, either Torque (Android) or DashCommand (Iphone). Torque Lite is free and will read codes. Torque Pro is $6 and will do a lot more than the $100 scanner mentioned above.

 

 

Idle's too high? Don't bogart so much, man! Oh wow.