Inlet Air Temperature Sensor Problem
The inlet air temperature sensor is malfunctioning or sending invalid values.
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What it means (plain English)
The computer reads the temperature of the air entering the engine to adjust fuel mix and timing. If the sensor fails, it can send the wrong temperature reading, affecting performance.
What the computer is actually seeing
The engine control module (ECM) expects a voltage signal between 0.5V (to indicate -40°C) and 4.5V (to indicate 125°C). Anything outside of this range triggers the code.
What a healthy reading looks like
Normal operation shows a voltage of around 1.5V to 3.5V based on ambient temperatures (e.g., 2.0V at 20°C).
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 connections to the inlet air temperature sensor for fraying or corrosion. If damaged, repair or replace as needed.
- 22. Disconnect the inlet air temperature sensor and measure the resistance. Expect around 2.5kΩ at 20°C. If it's outside the expected range, replace the sensor.
- 33. Reconnect the sensor and check the voltage signal with the engine running. It should vary between 1.5V and 3.5V. If not, check for short circuits or ground issues in the wiring.
Common causes
- Bad inlet air temperature sensor
- Open or shorted wiring to the sensor
- Poor electrical connection at the sensor
- Faulty ECM processing
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code present?
Yes, but performance may be affected and fuel efficiency can decrease.
Will this code come back if I just clear it?
It may come back if the underlying issue is not resolved.
Why does this code appear with SPN 110?
SPN 110 is often related to engine temperature issues that may arise from incorrect inlet air temperature readings.
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