"check engine" light..?
 

After fitting a new rad, water pump, hoses and coolant I've hot a check engine light..? Seems to run ok, from cold after ten mins hits just under 100 on the gauge. Hmmmmm any ideas?

If you have disconnected the A/C while doing the rad maybe the a/c fluid is low. Probably not related but if I go down a steep hill with low fluid the 'check' light comes on for several hours then goes off.

Have a read of this Jives and see if you can find out what the code is.

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

I don't know about you, but whenever i do work on the cooling system on my xj i always manage to get water everywhere and quite often set off the check engine light because of it. Perhaps you got water on a sensor or something??

same thing happen to me and the prob was i had a air lock in the thermostate housing where the sensor is just above the thermostate the fix was to losen the sensor to let air out do it back up and job done

when i found this out i could work out why it got to temp the fan should of came on but it didnt instead i got a check engine light
cheers dazza
all so i will add when filling up the cooling system the best place i have found to fill from is the heater pipe (not top rad hose)coming out of the thermostate so you are filling the head all the way up
i have tryed to fill from the rad but can never get all the air out