The Intake Air Temperature (IAT) sensor resistance changes in response to the intake air temperature. The Intake Air Temperature / IAT sensor measures the temperature of the air charge in the intake manifold. The ECM uses the data taken by the IAT sensor to set fuel injection timing and adjust the air-fuel ratio. Diesel engines with exhaust brakes are prone to IAT sensor fouling. Intake Air Temperature sensor fouling is due to combustion soot blowback taking place during the intake during valve overlap. The sensor resistance decreases as the surrounding air temperature increases. The IAT Sensor provides a signal to the Power Control Module to determine the temperature of the incoming air charge. The following symptoms can be related to a faulty IAT sensor due to loose connections, bad grounds, high resistance in the circuit, or opens in the circuit.
If your diesel engine performance has declined, it could be a dirty IAT Sensor. We recommend trying to clean your intake air temperature sensor to increase engine performance before replacement. Can improve the fuel mileage, and power output of your engine. We have found that improvements in overall engine performance, decreased exhaust gas temperatures, increased fuel economy, and power after cleaning carbon from the IAT sensor can restore the engines previous power and fuel economy output levels.
The Intake Air Temperature Sensor is also referred to as an Ambient Temperature Sensor in most diesel engines.