Intake Air Temperature Sensor Circuit Low Input
The engine control module is seeing a low voltage from the intake air temperature sensor.
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What it means (plain English)
The intake air temperature sensor helps the engine know how warm the air is coming in. If it's reading too low, it thinks the air is much colder than it really is, which can mess with how the engine runs.
What the computer is actually seeing
The ECM expects a voltage from the intake air temperature sensor (IAT) between 0.5V and 4.5V. A reading below 0.5V indicates a problem.
What a healthy reading looks like
IAT voltage should be between 0.5V to 4.5V; at room temperature (~68°F), expect about 2.5V.
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. Check the wiring and connector at the intake air temperature sensor. Look for damage, loose connections, or corrosion. If damaged, repair or replace it.
- 22. Measure the voltage at the sensor connector with the engine running. If below 0.5V, proceed to step 3; if normal, replace the IAT sensor.
- 33. Disconnect the IAT sensor and measure the resistance across its terminals. Compare with expected resistance at current temperature; if out of spec, replace the sensor.
- 44. If the sensor is good, check the ECM for faults. If programming or updates are required, do so according to manufacturer procedures.
Common causes
- Shorted wiring
- Faulty intake air temperature sensor
- Poor electrical connection or corroded connector
- ECM malfunction
Typical repair cost
$$
Related codes
Frequently asked questions
Can I drive it like this?
It's drivable, but fuel economy and performance may suffer, fix it sooner rather than later.
Will this code come back after I clear it?
If the underlying issue isn't resolved, it will likely return.
Why does this code sometimes pair with P0128?
Both may occur due to issues with temperature readings affecting engine performance.
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