P0111Intake Air Temperature Sensor 1 Circuit Range/Performance Bank 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Intake air temperature sensor 1 is the first air temperature sensor in the intake path; depending on the vehicle it is built into the mass air flow sensor, mounted near the air filter or, on some naturally aspirated GM engines, fitted in the intake manifold. Most versions are NTC thermistors in a 5 V divider: the hotter the air, the lower the signal voltage. P0111 is a plausibility fault: the signal is electrically valid but does not fit. The usual test runs at key-on after a long soak (Ford 6 h, GM 8 h): the intake air sensor is compared with other temperature sensors such as coolant, cylinder head, charge air cooler or IAT2, which should all read about the same. GM flags it above about 25 °C deviation, Ford above about 17 °C; Ford first confirms with a drive above 40 mph because sunshine can warm a sensor, and also sets P0111 if the air reads over 66 °C while driving. A detected block heater suspends the test. Two consecutive trips are needed.
- What you may notice
- Check engine light on
- Usually no noticeable symptoms
- Slightly changed idle, power or cold start possible
- Code often returns only after an overnight soak
- Likely causes
- LikelySensor drifting or stuck at one value (ageing, oil from crankcase ventilation)
- PossibleContact resistance at connector or wiring distorts the reading
- PossibleComparison sensor (coolant, IAT2, charge air cooler) wrong
- RareUndetected preheater, heat soak or sensor mounted near a heat source
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.