Air Temperature Sensor ( Ambient / Intake ): Description and Operation

Wiring Diagram:

DESCRIPTION
The IAT sensor is mounted in the air cleaner assembly. This sensor measures the temperature of the air entering the intake manifold and provides this information to the ECM/PCM.

OPERATION
The IAT sensor is a thermistor (a resistor whose resistance changes as a function of temperature). When the temperature is low, the resistance is high. The resistance decreases as temperature increases. The IAT sensor is a "two-wire" sensor with a reference signal voltage and a ground coming from the ECM/PCM.

The IAT sensor provides intake air temperature information to the ECM/PCM for use in calculating air density. The ECM/PCM uses IAT, MAP and engine speed to calculate the quantity of air flowing into the engine.

A failure in the IAT sensor circuit should set a DTC P0115 or P0116.

Legend

1. Crankshaft Position Sensor
2. Engine Coolant Temperature (ECT) Sensor
3. Intake Air Temperature (IAT) Sensor
4. Manifold Absolute Pressure (MAP) Sensor
5. Engine Control Module (ECM) / Powertrain Control Module (PCM)
6. Circuit Opening Relay
7. EFI-HTR Relay
8. Heated Oxygen Sensor 2(HO2S 2)
9. Oxygen Sensor (O2S)