P0112: Intake Air Temperature Sensor 1 Circuit Low (Bank 1)
P0112 means the engine computer sees a voltage from the first intake air temperature sensor that is lower than the sensor should ever produce. Usually the car stays drivable and the problem is a shorted sensor or a wire rubbing on metal, but power can be reduced on some vehicles, so get it checked soon.
You can drive, but get it checked soon
Many cars run almost normally with this code, but some retard the ignition, cut power or limit torque, and a cold start can be harder. Short trips to a repair shop are generally fine, while long trips or towing are better left until it is fixed.
What it means
The intake air temperature (IAT) sensor measures how warm the air entering the engine is. 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, located in the intake manifold. Most are thermistors (resistors that change with temperature) fed 5 volts by the engine control module. Hotter air gives a lower signal voltage. P0112 sets when that voltage drops below the valid range. That usually points to the signal wire touching ground or to a sensor that has shorted inside, which makes the module think the air is extremely hot (about 150 °C on GM). The module checks this circuit continuously, and GM needs the fault on two trips before setting the code. Some systems then substitute the coolant temperature, capped at 40 °C, and limit torque.
Likely causes
- Signal wire shorted to ground (chafed insulation)Very likely
A wire rubbing through its insulation against metal pulls the signal voltage to zero, which the module reads as extremely hot air.
- Sensor shorted internallyVery likely
A failed thermistor can drop to very low resistance and produce the same low voltage.
- Moisture or corrosion in the connectorPossible
Water or corrosion can create a path to ground or alter the signal at the plug.
- Engine control module faultyLess likely
A fault inside the module can misread the circuit, but this is rare compared with wiring and sensor problems.
What you may notice
- Check engine light on
- Usually hardly noticeable
- Retarded ignition, reduced power or torque limit on some systems
- Harder cold start possible
What to check, cheapest first
- 1Look at the IAT sensor and its connector (near the air filter, in the mass air flow sensor, or in the intake manifold, depending on the vehicle) for loose, wet, or corroded terminals. · you can do it
- 2Inspect the visible wiring to the sensor for chafed, pinched, or melted insulation, especially where it touches metal or engine parts. · you can do it
- 3Unplug the connector, clean any corrosion, let it dry, reconnect firmly, then clear the code and see if it returns. · you can do it
- 4Read the IAT value with a scan tool. A reading that is extremely hot on a cold engine confirms the low-voltage fault. · mechanic
- 5Unplug the sensor and watch the reading. If it changes to a very cold or open-circuit value, the sensor is shorted; if it stays hot, the wiring is shorted to ground. · mechanic
- 6Test the sensor's resistance and the wire for a short to ground, repair or replace the sensor or wiring, and only then consider the control module. · mechanic
Related codes
Frequently asked questions
Can I drive with a P0112 code?+
Usually yes for short distances, but some vehicles reduce power or retard ignition, and a cold start may be harder. Have it fixed soon.
Can a loose gas cap cause P0112?+
No. P0112 is an electrical fault in the air temperature sensor circuit, not a fuel vapor leak.
Will P0112 pass an emissions test?+
Unlikely. The code turns on the check engine light and is emissions-relevant, and the system needs a drive cycle after repair to confirm the fix before it is ready for testing.
How hard is it to fix?+
Often easy and doable at home. The estimated time is about 20 minutes to 1.5 hours, depending on whether it is a sensor swap or a wiring repair.
Written with the help of AI from the public OBDex definition (CC0). Each make may use the code differently. Updated: 2026-11-10