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.
IAT In MAF Sensor, Checking: Notes
The Mass Air Flow sensor and the Intake Air Temperature sensor are combined as a unit and are serviced as an assembly.
Use only gold-plated terminals when servicing terminals in the electrical harness connector of the MAF/IAT sensor -G70/G42-.
Special tools and workshop equipment required
- Multimeter.
- Wiring diagram.
Test procedure
-- Observe safety precautions. Refer to SAFETY PRECAUTIONS
-- Observe Clean Working Conditions. Refer to CLEAN WORKING CONDITIONS
-- Perform a preliminary check to verify the customers complaint. Refer to 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:
| Diagnostic text | Specified value | |||
|---|---|---|---|---|
| Intake Air Temperature (IAT) | approx. ambient air temperature | |||
If the specified value was obtained:
-- Fault may be intermittent. Check for proper connection, damaged wiring or loose terminals.
If the specified value was Not obtained:
Checking internal resistance
-- Disconnect the MAF/IAT sensor -G70/G42- electrical harness connector.
-- Using a multimeter, check the MAF/IAT sensor -G70/G42- terminals 3 to 4 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 the specified values were Not obtained:
-- Replace the MAF/IAT sensor -G70/G42-.
If the specified values are obtained, continue the test according to the following table:
| Indicated reading | Cause | Test |
|---|---|---|
| approx. - 40 °C to -46 °C | Open circuit or short circuit to (B+) | IAT IN MAF SENSOR, CHECKING => Testing if display approx. - 40° C to - 46° C: |
| approx. 140 °C | Short circuit to Ground (GND) | IAT IN MAF SENSOR, CHECKING => Testing if display approx. 140° C: |
Use the Manual With the Right Hardware
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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.
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