Applys to all 98.5 and up Cummins.The intake air temp sensor is located on the drivers side of the motor just above the lift pump and rearward of the fuel filter on the intake manifold. The IAT sensor reads the manifold air temp and sends a signal to the ECM to regulate intake ait grid heaters,fuel timing,fuel control, As fuel to air temps vary the sensors resistence changes the signal to the ECM. It has been my experience that if an exhaust brake is used that the IAT can become fouled with soot and the sensor becomes inaccurate, I personally clean mine every 10k miles with carburator cleanor, this make the allmighty Cummins happy and idles better as well as better overall performance including MPG.