Ok- the check engine soon light comes on when the on-board computer detects a fault in either engine driveability or performance, transmission control or transmission, or emissions control system. There are literally hundreds of reasons that the check engine light can be set- ranging from a vacuum hose leak, engine mis-fire, loss of engine compression, on of dozens of engine sensors, transmission solenoid or control module, internal transmission failure, emissions leak, or main computer malfunction.
The only way to find out what is causing the check engine light to come on is by having the on-board computer read with a diagnostic scanner.You can either take it into a shop and pay for this test. They will perform the diagnostic scan, and then do the necessary diagnostic troubleshooting to isolate problem. Or, you can take it by an Autozone, or most other parts stores, and they will do the diagnostic scan for FREE. they will tell you what the trouble code number is XXXXX what it generally refers to. BUT, they cannot do the diagnostic troubleshooting necessary to determine what part, if any, has failed, or whether it is an open/short in wiring, or other cause of problem.
If you choose to have Autozone do the scan, you can re-open this question and post the trouble code number here(the post will come directly to me), and i will give you the steps for troubleshooting and repairing the problem, or advise that this is something that can only be dealt with at a repair shop. i will do this for no additional charge(once original Accept is made) and continue to help until problem resolved.
If your vehicle is still under the factory warrany, I would suggest taking it into a Jeep dealer for diagnostic and any repair.