Inlet Air Temp Sensor 1 - Voltage High
The engine control module (ECM) sees an unusually high voltage reading from the inlet air temperature sensor.
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What it means (plain English)
The inlet air temperature sensor measures how hot the air entering the engine is. If it senses too high a voltage (over 4.5 volts typically), it means there's a problem with the sensor or its wiring.
What the computer is actually seeing
The ECM detects a voltage level from the inlet air temperature sensor that is above its normal operating range, usually triggering a fault at every key cycle where the voltage exceeds around 4.5 volts.
What a healthy reading looks like
Normal voltage range from the inlet air temp sensor should be between 0.5 volts and 4.5 volts, depending on temperature.
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 inlet air temperature sensor for damage or corrosion. Decision: If damaged, repair or replace wiring; if good, proceed to 2.
- 22. Disconnect the inlet air temperature sensor and measure the voltage at the connector while the ignition is on. Expected: Should be less than 4.5 volts. Decision: If over 4.5 volts, check the wire harness for shorts; if within range, proceed to 3.
- 33. Replace the inlet air temperature sensor. Decision: If code clears after replacement and voltage is normal, the issue is resolved; if code returns, further diagnose the ECM.
Common causes
- Shorted sensor wire
- Faulty inlet air temperature sensor
- Poor electrical connection at the sensor
- ECM malfunction or software issue
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended to drive long distances, as it may affect engine performance and fuel efficiency.
Will this code come back after clearing it?
If the underlying problem isn't fixed, it likely will return after a few key cycles.
Why does this code sometimes pair with SPN 1378?
SPN 1378 indicates a low voltage reading from the same sensor, showing that both extremes of sensor failure are possible.
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