P0111: Intake Air Temperature Sensor 1 Circuit Range/Performance (Bank 1)
The intake air temperature reading does not fit the other temperatures or does not change as expected.
Normal risk
Safe to drive. Have it checked at the next opportunity.
Short answer · Can I keep driving with P0111?
Yes. The effect on driving is usually small, but fuel use can rise a little. Have the sensor checked at the next service.
What does P0111 mean?
Code P0111 means the intake air temperature signal is within its electrical range but implausible: for example, it differs too much from the coolant temperature after a long stop, or it stays fixed while the engine warms up. A drifting sensor or a poor connection is the usual cause.
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 P0111
Is the intake air temperature sensor part of the MAF sensor?
On many engines yes. Then the whole mass air flow sensor is replaced.
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.