Hey guys. I recently acquired a '99 TL. It has 109k miles on it. When I'm driving, especially on the highway, my outside temp increases a lot. The other day the initial temp was 83 and within 15 min it went to 93. Do you think that the engine is over heating? I don't feel any difference in performance. Or do you think that the sensor is messed up or the heat from the engine is being entrapped around the sensor? Thanks.

check coolent level
if thats ok go to a trusted mechanic and have a combustable gas leak test performed on your radiator....if it passes look for leaves or junk in the radiator if it fails...head gasket time :(