check engine light?

i have a 2000 sport, auto, 4.0...stock.
check engine light came on...how do i find out why?
thank you for your knowledge and ideas.
N
i tried the hold down odo button three on thing and it cycled 111111 thru 777777 (checking guages and stuff) then just went back to normal. CE light still on. checked gas cap as well. O2 sensors?

Try this with the self-diagnostics:

Key off, push and hold the odometer reset button
Turn key to run (not start) and back to off
Release odometer reset button and look for trouble code on odometer

If the guages cycle through thier test you released the odometer reset button too early. This method worked on our '98, if it doesn't for you then you'll need to find an OBDII Scanner. I gots one, but I'm not close.

check here for most procedures. Let us know what worked for you.

EDIT: http://go.jeep-xj.info/HowtoECUcodes.htm

I have to turn the key on then off 3 times releasing the reset button on the last time in ON position. My gauges cycle through their tests, then sends the error codes. The number shows in the OD readout and the CE light flashes teh number. 55 is the end of codes code.

thanks guys. i'm going to oregon again next week and so i took it to the family mech. who hooked me up. the code was related to the fuel evap system. we checked for vac leaks etc...
when we got the the filler neck and filler cap it turned out the seal in the filler cap had a ding in it. he put on a new gasket (freebee!) and everything checked out. the CE or MIL is such a 50/50 situation... the filler cap so simple yet could have been worse.
we inspected the cooling system while hte lid was up and my rad. fluid was brown like dirty oil. hmmmm. maintenace is the key!!!
thanks again for the replies and ideas.
Nim

The key-clicky trick won't work on '98s and newer. If you got a code, then it was just the "end of gauges diagnostics" code that you got. There are "some" 97's in which this will work on, and some it won't. Just depends on manufacture date.

You'll need to get access to and OBDII code reader to capture trouble codes.

For more info on which vechicles work with the key-clicky trick, read more about it here.

Ivan

The cooling system on jeeps is something else thats for sure. I just did both our 'new' 97 TJ's that we got this past winter and the coolant was almost black on both and stinky, I tend to think it was the original factory stuff. Nice and bright green now...

Ivan, the key clicky trick I described above worked fine to pull trouble codes from our '98 XJ.