P0112: Intake Air Temperature Sensor 1 Circuit Low
The intake air temperature sensor voltage is too low, so the computer is reading the incoming air as impossibly hot.
What P0112 means
The intake air temperature sensor is a thermistor whose resistance drops as air gets warmer. The engine computer feeds it 5 volts and reads the voltage that comes back. Hot air means low voltage; cold air means high voltage. P0112 sets when the signal stays below about 0.5 volts, which the computer reads as extremely hot air, while the coolant temperature reading is changing normally, according to RepairPal. The usual cause is a failed sensor or a wire shorted to ground. On many modern cars the IAT is built into the MAF sensor, so the fix may mean replacing that assembly. RepairPal also lists a dirty air filter and a faulty MAF among possible triggers. Shops compare IAT and coolant temperature on a cold engine, since both should start near outside temperature. They check for 5 volts and ground at the connector. It is not urgent, but wrong air temperature data affects fueling and timing.
Common symptoms
- Check engine light on
- Hard starting, especially when cold
- Hesitation on acceleration
- Poor gas mileage
- Often no noticeable symptoms
Most common causes
- Faulty intake air temperature (IAT) sensor
- Signal wire shorted to ground
- Damaged or corroded connector
- Faulty MAF sensor on vehicles where the IAT is built into it
- Very dirty air filter
What to check yourself first
Check whether your IAT sensor is separate or built into the MAF sensor. Inspect the connector and wiring. On a cold engine that has sat overnight, a scan tool should show intake air temperature close to the outside temperature and to the coolant temperature.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Replace intake air temperature sensor | $119-$142 | For a separate IAT sensor. On many cars it is part of the MAF sensor instead. |
| Replace mass airflow (MAF) sensor | $274-$381 | When the IAT sensor is built into the MAF and cannot be replaced alone. |
| Electrical diagnosis to find a wiring or connector fault | $122-$179 | For a chafed wire or bad connector, which RepairPal lists as a common misdiagnosis. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
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Related codes
- P0113 Intake Air Temperature Sensor 1 Circuit High
- P0101 Mass or Volume Air Flow "A" Circuit Range/Performance
- P0117 Engine Coolant Temperature Sensor 1 Circuit Low
- P0118 Engine Coolant Temperature Sensor 1 Circuit High
- P0100 Mass or Volume Air Flow "A" Circuit