I have a 2001 LS that indicates it's overheating but does not actually appear to be. The first time it happened the temp gauge spiked and the check engine temperature message came on. I pulled over right away and popped the hood only to discover it was not hot or leaking. Restarted and it was immediately back to normal. Now, if you run the center vent the fan will turn on and the guage will jump up along with the warning and reduced power mode. If you run the heater on it goes back to normal. If you start with heat if doesn't do it at all? It makes no difference if you are on dual or single zone and if the AC is on or off. If you are on the floor vent it happens and on the floor vent it does not unless you lower the temperature below 70 or so. Is there an obvious answer?