the IAT sensor is in the air flow sensor...... there is 2 type of IAT sesor one is IAt sensor alone and the other type is built-in with air flow sensor or MAP sensor.... it is easy to regonize. Air flow sensor or MAP sensor with 4 wire is with IAT sensor. If 3 wire either IAT sensor is at the intake air line or at the intake manifold or thw EMS is without IAT sensor.