Intake Air Temperature Sensor, Checking

Intake Air Temperature Sensor, Checking

Observe all safety precautions: => [ Safety Precautions ] Generic Scan Tool

View clean working conditions: => [ Clean Working Conditions ] Clean Working Conditions

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

Special tools, testers and auxiliary items required

• multimeter.

• Wiring diagram.

Test requirements

• The Engine Control Module (ECM) (J623) fuses OK.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• Vehicles with automatic transmission, shift selector lever into position "P" or "N".

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Ignition switched off.

Test procedure

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

Start diagnosis

- Connect the scan tool.

- Switch the ignition on.

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






If the specified value is not obtained:

- Continue the test according to the following table:






If the specified values are obtained:

- Remove engine cover. Refer to the appropriate service manual.

Checking internal resistance

- Disconnect the Intake Air Temperature (IAT) Sensor (G42) electrical harness connector - 1 -.





- Using a multimeter, check the Intake Air Temperature (IAT) Sensor (G42) terminals 1 to 2 for resistance.





Use the chart below for the specified values:

Specified values:






If any of the specified values are not obtained:

- Replace the Intake Air Temperature (IAT) Sensor (G42). Refer to the appropriate service manual.

°°Testing if display approx. -40 C or approx. -46 C:

- Disconnect the Intake Air Temperature (IAT) Sensor (G42) electrical harness connector - 1 -.





- Using a jumper wire, connect the Intake Air Temperature (IAT) Sensor (G42) electrical harness connector terminals 1 to 2.

- Check the value indicated on the scan tool display.





If indication jumps to approx. 140° C:

- End diagnosis and switch ignition off.

- Replace the Intake Air Temperature (IAT) Sensor (G42). Refer to appropriate service manual.

If indication remains at approx. -40° C or -46° C:

°Testing if display approx. 140 C:

- Disconnect the Intake Air Temperature (IAT) Sensor (G42) electrical harness connector - 1 -.





If indication jumps to approx. -40° C or -46° C:

- End diagnosis and switch ignition off.

- Replace the Intake Air Temperature (IAT) Sensor (G42). Refer to appropriate service manual.

If the indication remains at approx. 140° C:

Checking wiring

If the manufacturers test box is being used, perform the following step.

- Install the test box.

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

- Remove the Engine Control Module (ECM) (J623). Refer to appropriate service manual.

- 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 T60 terminals for resistance.










Specified value: 1.5 ohms Max.

If the specification was not obtained:

- Check the wiring for an open circuit, a short circuit to Battery (+), or an open circuit.

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

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

- Perform a road test to verify repair.

If the DTC does not return:

Generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was not OK:

- Replace the Engine Control Module (ECM) (J623). Refer to appropriate service manual.

Final procedures

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

1. Check the DTC memory. => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

2. If necessary, erase the DTC memory. => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

3. If the DTC memory was erased, generate readiness code. => [ Readiness Code ] Readiness Code.