Sensor is located in the airdam, just to the driver's side of center. If you lay on your back and wiggle under the car, you'll see it a little bit to your left, an inch or two from your nose.

If it's out of place (as the previous posters have noted), that could certainly account for the high reading. It seems like a fragile connection; I taped mine in place a couple months ago.

The sensor and the computer relay an average temperature, so it takes a few seconds in motion to get an accurate reading. If your car is idling (especially with the a/c on) the sensor is reading the temperature of the warm air circulating around the front of your car. This effect can be magnified by warm air rising from sun-basted black pavement.

Good luck.