P0111 Intake Air Temperature Sensor 1 Circuit Range/Performance

P0111 indicates a range or performance problem in intake-air-temperature sensor 1. The signal changes implausibly or does not match expected temperature behavior.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace the sensor from one odd reading; range/performance faults need trend and plausibility checks.

Symptoms of P0111

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0111

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Compare IAT to ambient temperature after a cold soak and watch how it changes as underhood temperature rises.
Inspect the sensor location, airbox sealing, connector fit, wiring, and shared MAF/IAT harness condition.
Review freeze-frame data to see whether the fault set after heat soak, high load, or sudden airflow changes.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.