Engine Ambient Air Temperature Sensor Circuit Low Input
The ECM detects a low voltage signal from the ambient air temperature sensor.
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What it means (plain English)
The engine's computer is reading that the temperature sensor for the outside air is sending a signal that is too low, indicating a possible fault or disconnection in the circuit.
What the computer is actually seeing
The Engine Control Module (ECM) expects a voltage signal from the air temperature sensor typically between 0.5V and 4.5V. A reading below 0.5V is interpreted as a failure.
What a healthy reading looks like
Normal voltage range for ambient air temperature should be 0.5V to 4.5V; temperatures from -40°C to +125°C correspond to these voltages.
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 connectors for the ambient air temperature sensor for any visible damage or corrosion.
- 22. Measure the voltage at the sensor connector with the key on and engine off. Expected voltage should be between 0.5V and 4.5V. If it's below 0.5V, proceed to the next step.
- 33. Disconnect the sensor and test for a short to ground in the wiring harness. Use a multimeter to check resistance; it should be infinite (no continuity).
- 44. Reconnect the sensor and test the sensor itself. Use a temperature simulator or compare with ambient temperature to see if the resistance changes. If it doesn’t, replace the sensor.
- 55. If all other checks are good, replace the wiring harness.
Common causes
- Wiring harness short to ground
- Corroded connectors at the ambient temperature sensor
- Faulty ambient air temperature sensor
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but it's recommended to fix it soon as it can affect fuel efficiency and performance.
Will this code come back after clearing?
It may return if the underlying issue isn't fixed, like a faulty sensor or damaged wiring.
Why is this code sometimes paired with other codes?
It's common for multiple sensors to fail or have related issues, especially in the same circuit.
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