Air Temperature Sensor ( Ambient / Intake ): Testing and Inspection

Intake Air Temperature Sensor, Checking

The Intake Air Temperature (IAT) Sensor (G42) and the Manifold Absolute Pressure (MAP) Sensor ( G71) are integrated into one unit and cannot be serviced separately.

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram

Test requirements

• Fuses for engine electronics OK.

• Battery voltage at least 12.5 V.

• The ignition switched off.

Checking function

- Connect the scan tool.

- Switch the ignition on.

- Using the scan tool, check the intake air temperature:





If the specified value is not obtained:

- End diagnosis and switch the ignition off.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ General Diagnosis ] General Diagnosis.

Start diagnosis

- Remove the rear engine cover - arrows -.





Checking voltage supply

- Disconnect the Intake Air Temperature (IAT) Sensor (G42) electrical harness connector- 4 -.





Switch the ignition on

- Using a Multimeter, check the Intake Air Temperature (IAT) Sensor (G42) electrical harness connector for voltage.









Switch the ignition off

If the specified values are obtained:

- Replace the Intake Air Temperature (IAT) Sensor ( G42).

If specified values are not obtained:

Checking wiring connections

If the manufacturers test box is being used. Perform the following step.

- Install the test box. Refer to Fuel Injection and Ignition Repair Information.

If the manufacturers test box is not being used. Perform the following step.

- Remove the Engine Control Module (ECM) (J623 ). Refer to => [ ECM, Removing and Installing ] ECM, Removing and Installing.

- Using a Multimeter, check the Intake Air Temperature (IAT) Sensor (G42) electrical harness connector terminals to the Engine Control Module (ECM) (J623) electrical harness connector terminals for an open circuit.









Specified value: 1.5 ohms max.

If the specification was not obtained:

- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

- Check the electrical harness connector for damage, corrosion, lose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring and if the voltage supply was OK:

- Replace the Engine Control Module (ECM) (J623 ). Refer to => [ ECM, Removing and Installing ] ECM, Removing and Installing.

- Install the rear engine cover - arrows -.





Final procedures

After repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

- End of diagnosis.