Engine Intake Air Temperature Sensor - Voltage Above Normal
The engine intake air temperature sensor is reporting a voltage that is too high.
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What it means (plain English)
The Intake Air Temperature (IAT) sensor measures how hot the air going into the engine is. If it reads a voltage that's higher than expected, it could mean the sensor is sending faulty information or is damaged.
What the computer is actually seeing
The Engine Control Module (ECM) gets a higher-than-normal voltage reading from the IAT sensor, typically over 4.5 volts, indicating a potential short or sensor fault.
What a healthy reading looks like
Normal IAT voltage values range from 0.5 to 4.5 volts depending on temperature changes; higher than 4.5 volts suggests an issue.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connector for the IAT sensor for any visible damage or corrosion. Decision Point: Is wiring/connectors good? Yes = Next step, No = Repair/replace damaged parts and retest.
- 22. Measure the voltage at the IAT sensor connector with the key on, engine off. Expected voltage should be between 0.5 and 4.5 volts. Decision Point: Is the voltage over 4.5 volts? Yes = Replace the sensor, No = Next step.
- 33. With the engine running, measure the IAT voltage again as air temperature changes. It should vary appropriately. Decision Point: Does the voltage change as expected? Yes = Check for ECM issues, No = Replace the IAT sensor.
Common causes
- Shorted wiring in the IAT sensor circuit
- Faulty IAT sensor
- Corrosive damage at the sensor connector
- Open ground in the sensor circuit
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's drivable but fix soon to avoid performance issues and increased emissions.
Will this code come back after a reset?
It may if the underlying issue isn't resolved; monitor sensor readings.
Why does this code pair with others like SPN 6789?
Issues in the IAT circuit can cause multiple sensor faults if the ECM detects abnormal readings.
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