P0112: Intake Air Temperature Sensor 1 Circuit Low
The intake air temperature sensor signal is at the bottom of its range, which reads as very hot air.
Normal risk
Usually safe to drive. Have it checked at the next opportunity.
Short answer · Can I keep driving with P0112?
Yes. The engine uses a substitute temperature and usually runs normally, though starting and economy may suffer. Have the wiring and sensor checked.
What does P0112 mean?
The intake air temperature sensor is a thermistor whose resistance falls as temperature rises. A very low signal voltage reads as extremely hot air, so P0112 usually means a short to ground in the wiring or a failed sensor.
What the car does when the code is set
The check engine light comes on and the engine uses a fixed substitute temperature. Most drivers notice no difference. Some cars start less easily in very cold or very hot weather or use slightly more fuel.
How the system works
The intake air temperature sensor is a thermistor whose resistance falls as the air gets warmer. The engine control unit feeds it a reference voltage of about 5 volts and reads how much is left: a high voltage means cold air, a low voltage warm air. The reading is used to correct fuel quantity and ignition timing, because cold air is denser than warm air. If the signal is stuck at either end of its range, the control unit recognises a circuit fault and replaces the reading with a fixed value.
Common symptoms
Possible causes
Listed without ranking. The cause on your car depends on make, engine and mileage — see the maker notes below.
- Open circuit or unplugged sensorA broken wire or loose connector makes the reading jump to its coldest value.
- Corroded connectorCorrosion adds resistance to the circuit.
- Faulty sensorThe sensor resistance no longer changes correctly with temperature.
- Wiring damageChafed wires near the intake or engine.
How it is diagnosed
- Compare with outside temperatureWith a cold engine, the intake air temperature should be close to the outside temperature. A reading of about −40 °C usually means an open circuit.
- Check the connectorUnplug the sensor (it is often part of the air-flow sensor) and look for corrosion and bent pins.
- Measure resistance and voltageCompare the sensor resistance at a known temperature and the reference voltage with the service data.
- Repair and clearAfter a repair, clear the code and check that the reading follows the real temperature.
Questions about P0112
Why does the scanner show a very high air temperature?
A short to ground pulls the signal down, which the system reads as very hot air. It is a sign of a circuit fault, not real temperature.
Will this code affect fuel economy?
Slightly. The engine uses a substitute temperature, so the mixture is less precisely matched to the real air density.
Is the sensor part of the air-flow sensor?
On many cars it is, so the whole air-flow sensor is replaced. On others it sits separately in the intake duct or manifold.