Intake Air Temperature Sensor 1 Circuit Range/Performance
The P0111 code means the vehicle's onboard diagnostic system has detected: Intake Air Temperature Sensor 1 Circuit Range/Performance. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- easy
- Estimated cost
- $15-$150
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Common Symptoms
- Check Engine Light on
- Slightly rough cold starts
- Minor fuel economy reduction
- No major drivability issues
Probable Causes (Ranked by Likelihood)
- IAT sensor reading does not correlate with coolant temp on cold start Very High
- Partially failed sensor giving erratic readings High
- IAT sensor located in a heat-soak area Moderate
- Wiring intermittent fault Moderate
Common Fixes by Vehicle
What techs usually find when diagnosing P0111 on specific vehicles — tap your vehicle for the fix and the exact part:
2005-2014 Ford F-150/Mustang 4.6L/5.0L Easy DIY
IAT sensor reading stuck/unresponsive during warm-up — typically the integrated IAT portion of the MAF sensor has failed. Replace the MAF/IAT combo sensor. Do not clean with anything but MAF-specific cleaner.
Labor: 15-30 min2004-2014 GM 5.3L/6.0L/4.8L (Silverado, Tahoe) Easy DIY
IAT performance failure with no clear cause — replace the intake air temperature sensor (separate from MAF on these engines). Sensor is in the intake duct. Inspect the 2-pin connector for corrosion.
Labor: 10-15 min2007-2015 GM 3.6L V6 (Traverse, Acadia, Enclave, CTS) Easy DIY
IAT sensor range/performance — commonly caused by oil/coolant fouling of the IAT sensor tip due to a leaking PCV diaphragm. Clean or replace IAT, then address PCV issue (typically integrated into valve cover on 3.6L).
Labor: 15 minFrequently Asked Questions
Will P0111 affect my fuel mileage?
Slightly. If the IAT reads too cold, the ECU may over-enrich the mixture. If too hot, it may lean it out. The effect is usually minor unless the reading is at an extreme value.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
After a cold soak, compare IAT and ECT readings at startup. Both should be within 10-15 degrees F of ambient temperature.
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Monitor IAT during a test drive. It should rise moderately as intake duct heats up.
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An IAT reading that does not change during driving or is fixed at an extreme value indicates sensor failure.
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Replace IAT sensor if readings are erratic or unresponsive.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- Ford vehicles with integrated IAT/MAF
- General Motors 4-cylinder platforms
- Honda CR-V and Pilot
- Nissan Sentra
- Subaru Legacy
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