Intake Air Temperature Sensor, Checking

Intake Air Temperature Sensor, Checking

• Use only gold-plated terminals when servicing terminals in the electrical harness connector of the IAT sensor (G42).

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test procedure

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

Start diagnosis

- Connect the scan tool.

- Engine MUST be at room temperature.

- Switch the ignition On.

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






- Switch the ignition Off

If the specified value was obtained:

- Fault is intermittent. Check for proper connection, damaged wiring or loose terminals.

If the specified value was Not obtained:

Checking internal resistance

- Disconnect the IAT sensor (G42) electrical harness connector.

- Using a multimeter, check the IAT sensor (G42) terminals 1 to 2 for resistance.

Use the chart below for the specified values:

Specified values:






If the specified value was Not obtained:

- Replace the IAT sensor (G42). Refer to the Repair Information.

If the specified values are obtained, continue the test according to the following table:






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

- Disconnect the IAT sensor (G42) electrical harness connector.

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

- Turn the ignition switch On.

- Check the value indicated on the scan tool display.

- Switch the ignition Off.

If indication jumps to approx. 140 °C:

- Replace the IAT sensor (G42). Refer to the Repair Information.

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

Checking wiring

- Remove the Engine Control Module (ECM) (J623). Refer to the Repair Information.

- Disconnect the ECM harness.

- Using a multimeter, check the IAT sensor (G42) electrical harness connector terminal 1 to the Engine Control Module (ECM) (J623) electrical harness connector T60 terminal 42 for an open circuit or a short to voltage, refer to the wiring diagram.

Specified values: Circuit continuity; 1.5 ohms max; Circuit voltage = 0 volts when disconnected from ECM (with ignition turned on).

If the specified value was Not obtained:

- Check the wiring for an open, high resistance or short circuit to Battery positive.

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

- If necessary, repair the faulty wiring connection.

If the specified value was obtained:

- Using a multimeter, check terminal 2 of the IAT sensor to engine ground.

Specified value: 1.5 ohms Max

If the specified value was Not obtained:

- Check the wiring from the IAT sensor terminal 2 to the ECM terminal T60 - 14 for an open circuit, short or high resistance.

- 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:

- Replace the Engine Control Module (ECM) (J623). Refer to the Repair Information.

°Testing if display approx. 140 C:

- Disconnect the IAT sensor (G42) electrical harness connector.

- Turn the ignition switch On.

- Check the value indicated on the scan tool display.

- Switch the ignition Off.

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

- Replace the IAT sensor (G42). Refer to the Repair Information.

If the indication remains at approx. 140° C

- Remove the Engine Control Module (ECM) (J623). Refer to the Repair Information.

- Disconnect the ECM harness.

- Using a multimeter, check the IAT sensor (G42) electrical harness connector terminal 1 to engine ground.

Specified value: OL or no continuity.

If the specified value was Not obtained:

- Check the wiring for a short circuit to Ground.

- If necessary, repair the faulty wiring connection.

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

If no malfunction is detected in the wiring and the sensor resistance was OK:

- Replace the Engine Control Module (ECM) (J623). Refer to the Repair Information.

Final procedures

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

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

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

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