Where is the IAT Sensor in a 1999 Chevrolet Cavalier 2.4L DOHC?

The Intake Air Temperature senor is a temperature-sensitive resistor Chevrolet mounted in the intake system of the 1999 Cavalier. The powertrain control module sends this sensor a 5-volt reference signal, and as the temperature rises or lowers in the intake, the IAT sensor creates lower or higher resistance, respectively. The 5-volt reference then travels back to the PCM after the resistance in the IAT has lowered the voltage. The PCM reads this voltage and makes adjustments as needed to the fuel injection system. This is a far cry from the days of old school fuel-air-spark-boom internal combustion engines. Regardless of its complex function, locating, testing and replacing the IAT sensor on a 1999 Cavalier 2.4-liter engine is a simple task.

Instructions

Locating the Intake Air Temperature Sensor

1

Open the Cavaliers hood.

2

Find the air filter box on the front drivers side of the engine compartment. Find the tube linking the air filter box to the engine; this is the air box outlet tube.

3

Trace the hose toward the engine until you find a small electrical sensor pressed into the hose. This sensor is the IAT sensor.

Self-Testing the Intake Air Temperature Sensor

4

Pry upward on the locking tab on the IAT sensors wiring harness using a flat-head screwdriver, and hold the tab upward. Unplug the wiring harness from the IAT sensor.

5

Turn the ignition to the Run position but do not start the engine. Turn the multimeter to the voltage-testing feature. Press the negative probe on the negative battery cable or a bare-metal ground; press the positive wire on the pin that has the gray wire attached to it. This wire must have a reading of roughly 5 volts. If there is not 5 volts coming from this wire, then there is a short in the wire or the Cavalier has a failed powertrain control module. Repair the fault, if applicable, and proceed to the next step.

6

Look inside the receptacle on the IAT sensor and find the two prongs.

7

Turn on the multimeter and set it to measure ohms. Compare the ohms reading on the multimeter to the IAT sensor resistance value chart. If the resistance measured is not inside of the specifications indicated, the IAT sensor needs to be replaced.

Replacing the Intake Air Temperature Sensor

8

Pry upward on the locking tab on the IAT sensors wiring harness using a flat-head screwdriver, and hold the tab upward. Unplug the wiring harness from the IAT sensor.

9

Pull upward on the IAT sensor with a slight twisting motion to remove it from the air box outlet tube.

10

Align the new IAT sensor with the hole in the air box outlet tub and press the sensor into the tube until its flange seats flush against the tube. Plug the harness into the IAT sensors receptacle.