first check the sending unit. it is all the way to the rear just behind or next to the valve cover. one wire. could be disconnected. the one up front with the two wires is not the one that sends to the temp gauge.
I don't know what they tried to sell you but neither the temp sending unit or the temp sensor sending unit cost that much.......It was dark outside and I was in a hurry because the ole lady was mad at me for buying the jeep. I will check them both out. If the sending unit is connected and I'm still getting no reading should I just replace it. $43.99 at orielly
Check for a break in the wire of a loose or dirty connection to the sensor. Mine had the same problem, replaced the sensor problem fixed. After looking at the old sensor found that it was broken inside and would only make connection sometimes.k i have a 94 yj with the 2.5 my temp gauge isnt working correctly. No its not the sensors. It goes up to 100° will not read higher. I jiggle the wire harness on the fire wall n it come on but as soon as i start driving or hit a bump it goes back to 100° anyone know what to look at. This issue is causing my motor to dump to much fuel into the injectors which in terms is filling my oil up with fuel which will blow my motor very soon