Eliminate the factory Intake Air Heater or IAH with this Driven Diesel Intake Air Heater Plug. This plug will also give you a convenient area to pull boost readings from and or add water methonal injection. The factory Air Intake Heater is located in the Cold Side Inlet of the intake manifold on the engine and blocks approximately 20% of the intake path. Since the heater is RARELY active due to the very specific circumstances under which the PCM enables it, many customers have removed it in and replaced it with a plug like this to improve air flow.