Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Intake Air Temperature Sensor, Checking: Notes
Observe all safety precautions: SAFETY PRECAUTIONS
View 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 and workshop equipment required
- multimeter.
- Wiring diagram.
- Cool spray (commercially available).
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 .
Start diagnosis
-- Connect the scan tool.
-- Switch the ignition on.
-- Using the scan tool, check the intake air temperature:
| Diagnostic text | Specified value | |||
|---|---|---|---|---|
| Intake Air Temperature (IAT) | approx. ambient air temperature | |||
If the specified value is not obtained:
-- Continue the test according to the following table:
| Indicated | Cause | Test |
|---|---|---|
| approx. -40° C or approx. -46 °C | Open circuit or short circuit to (B+) | INTAKE AIR TEMPERATURE SENSOR, CHECKING => Testing if display approx. -40 °C or approx. -46 °C: |
| approx. 140 °C | Short circuit to Ground (GND) | INTAKE AIR TEMPERATURE SENSOR, CHECKING => Testing if display approx. 140 °C: |
If the specified values are obtained:
-- Remove engine cover. Refer to the appropriate service information.
-- Remove the Intake Air Temperature (IAT) Sensor -G42-. Refer to the appropriate service information.
-- Spray the Intake Air Temperature (IAT) Sensor -G42- with a commercially available cool spray while observing the temperature value on the scan tool.
The temperature value must decrease.
-- End diagnosis and switch the ignition off.
If the intake air temperature does not decrease:
-- Replace the Intake Air Temperature (IAT) Sensor -G42-. Refer to the appropriate service information.
If the intake air temperature does decrease:
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:
| IAT Temperature vs Resistance | ||
| Temp (C) | min value ohms | max value ohms |
| - 40 | 31811 | 37560 |
| - 35 | 22941 | 26863 |
| - 25 | 12415 | 14289 |
| - 15 | 6958 | 7880 |
| - 5 | 4036 | 4495 |
| 0 | 3120 | 3442 |
| 5 | 2422 | 2655 |
| 15 | 1519 | 1623 |
| 25 | 968 | 1031 |
| 35 | 629 | 676 |
| 45 | 419 | 455 |
| 55 | 286 | 314 |
| 65 | 195 | 217 |
| 75 | 136 | 155 |
If any of the specified values are not obtained:
-- Replace the Intake Air Temperature (IAT) Sensor -G42-. Refer to the appropriate service information.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.