Intake Air Temperature Sensor, Checking

Intake Air Temperature Sensor, Checking

Observe all safety precautions: => [ Safety Precautions ] Safety Precautions

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.

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

- Disconnect the connector -1- from the Mass airflow sensor (G70) , and remove the Air Filter Housing. Refer to appropriate service manual.

- Switch the ignition ON.

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

If the specified value was not obtained:

- Continue test according to the following table:

If the specified value was obtained:

Checking internal resistance

- Disconnect the Intake Air Temperature (IAT) Sensor (G42) electrical harness connector - 6 -.

- 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 value's were not obtained:

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

- Go to Final procedures

If the specified values were obtained:

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

- Go to Final procedures

°Testing if scan tool display is approx. - 40.0 C

- Disconnect the Intake Air Temperature (IAT) Sensor (G42) electrical harness connector - 6 -.

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

- Switch the ignition on.

- Check the value indicated on the scan tool display.

Specified value: scan tool display approx. 140.0° C

- End diagnosis and switch ignition off.

If the specified value was obtained:

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

- Go to Final procedures

If the specified value was not obtained:

Checking wiring

- Remove the Motronic 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 Motronic Engine Control Module (ECM) (J623) electrical harness connector T60 terminals for an open circuit according to the wiring diagram.

Specified value: scan tool display approximately -40.0° C

- End diagnosis and switch ignition off.

If the specified value was obtained:

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

- Go to Final procedures

If the specified value was not obtained:

Checking wiring

- Remove the Motronic 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 Motronic Engine Control Module (ECM) (J623) electrical harness connector T60 terminals for an open circuit according to the wiring diagram.

Specified value: 1.5 ohms Max.

If the specified value was not obtained:

- Check the wiring for a short circuit to Battery voltage, or an open circuit.

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

- If necessary, repair the faulty wiring connection.

- Go to Final procedures

If the specified value was obtained:

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

Final procedures

- Reinstall the engine cover and Air Filter Housing, if necessary. Refer to the appropriate service manual.

- After the 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 Modes 01 - 0A.

2. If necessary, erase the DTC memory. => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 0A.

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