So last night I was driving on the freeway home and all the sudden my 99 2.5L was overheating. I pulled over and popped the hood to check it out. Coolant level was OK, nothing seemed out of place. Also the engine didn't really seem abnormally hot; it was pretty much at normal operating temperature. But as to not take any chances I let it sit for a few minutes and disconnected the battery. After about 3 minutes I started her back up and the gauge read at the normal operating temperature.

So did my car actually overheat and didn't feel that hot because I don't know what I"m doing? Or did the coolant temp. sensor go bad? Or is my dash on the fritz? Anyone have any experience with this? Thanks for the help!

 

Did you check the coolant level in the motor? And was the fan running when the engine was overheating?

 

There is a possibility that you have clogged passages in the radiator, or worse, in the head itself.
This will keep the antifreeze from reaching the radiator to give up it's heat, which will dissipate quick enough once the engine is off.
I also ran into issues where it would be a little low, get an air bubble in the engine passages, and block the flow of coolant in short bursts. If this is the case, with the car cold, take the radiator cap off, start the car, and slowly pour coolant into the swirl. If there is air bubbles, it may spit back out, so watch out for that.

 

The hose leading to the thermostat housing was on a little too far, it looked like. I reset that and retightened the clamp, as well as added more coolant and let the bubbles work their way out. Drove it for about 4 hours last night, 1 hour today on the way to work in conditions from stop-and-go to 75 mph highway speeds. The needle never even made it to the halfway mark on the gauge, and I've had nothing leaking out (I gave the undercarriage a good blast with the hose and some degreaser). Even put a piece of cardboard under there last night before I went to bed and saw no evidence of any fluids when I checked this morning.

I think the hose being a little askew may have been letting hot air into the system, which would have entered right next to the CTS and could have potentially thrown off the readings. Also I just had the valve cover changed by a mechanic; he probably disconnected the CTS and that hose in order to make getting the cover back on easier. Everything seems fine for now *knock on wood* so I can get back to the other problems this car gives me

Thanks for the help, though! Always love posting here.