My overhead temperature is initially accurate but after a couple of hour drive in the snow it just keeps going up. Not sure where it is located, is it getting heat from inside the cab or engine compartment?

 

OAT sensor is mounted in front of the truck, driver side between the headlight and condenser. Guessing it's getting loaded up with ice and snow which can insulate the sensor from the true air temperature.

 

Yeap, it bolts to the top headlight bolt on the drivers side. Pop the hood, you can't miss it.

 

This issue finally surfaced. The wires going to the sensor could use a little more slack, they are bent at a 90deg and them go in. Over time the outer coating cracked, expose the wires and the corroded to the point it does not work. I bought a new pig tail and spliced it in but is showing 130 or -40. I have not drove it so not sure if it samples every few minutes and may work itself out or not.