P0111Generic code

P0111 Code: Intake Air Temperature Sensor Circuit Range/Performance

The P0111 code means the IAT sensor reading is electrically valid but does not agree with the other sensors. It is usually caused by a sensor that reads wrong or gets stuck, although it can also be a real condition in the engine.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$15 to $150
Difficulty
Easy
System
Air and Fuel
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0111 code means

The intake air temperature (IAT) sensor sits in the air filter box, in the intake duct, or built into the MAF sensor. The computer relies on it because it adjusts the amount of fuel and the spark advance according to air density.

In this case the signal is within the electrical limits, but it is not believable. The computer compares the IAT with other data. With a cold engine after several hours parked, the IAT should match the ambient temperature and agree with the coolant (ECT) sensor within a few degrees. If the difference exceeds what is allowed for the programmed time, the P0111 code is stored. It is not a cut wire. It is a sensor that reads wrong, freezes at one value or reacts too slowly, or else a real abnormal condition.

Remember that the code points to the circuit where the computer saw the anomaly, not necessarily the failed part. Check the wiring before you replace the sensor, and test the IAT sensor step by step as described below.

P0111 code symptoms

  • Check engine light on steadily.
  • In many cases you notice nothing while driving, just the light on the dash.
  • Companion codes for the same sensor may appear (low signal, high signal or intermittent).

Likely causes of the P0111 code

  1. Out-of-calibration or degraded sensor that gives a believable but wrong value.
  2. Real abnormal condition, such as very hot air from an intake that draws from the engine bay, or a clogged intercooler.
  3. Dirty sensor or one with deposits that make it respond slowly.
  4. High resistance in the connector from corrosion, which shifts the reading.
  5. Computer software. Some manufacturers published updates for false range codes.
  6. Complementary check: a dirty MAF or a bad air filter will not set this code, but they are worth inspecting because on many models they share the connector.

How to diagnose the P0111 code step by step

  1. Read the sensor live data and compare it with what is expected. With a cold engine after several hours parked, the IAT should match the ambient temperature and agree with the coolant (ECT) sensor within a few degrees.
  2. Inspect the connector. Unplug it, look for green, backed-out or oily pins, and plug it back in firmly.
  3. With the key on and the sensor unplugged, measure the reference at the connector. There should be about 5 V between the signal and ground.
  4. Jumper test. With the sensor unplugged, the scan tool should show about -40 °C (-40 °F). When you join the two connector pins with a wire, it should jump to more than 120 °C (248 °F). If it does, the wiring is fine and the problem is the sensor.
  5. Measure the sensor resistance and compare it with the technical data table at the current temperature.
  6. Do the wiggle test with the engine running. Move the harness and the connector while you watch the live data, because a jump shows you where the fault is.
  7. Check the continuity of each wire between the sensor connector and the computer connector with the key off.

How to fix the P0111 code

  • Correct the real condition if there is one (thermostat, level, leaks, fuel).
  • If the sensor reads wrong against a reference thermometer or gauge, replace it.
  • Look for technical bulletins or software updates from the manufacturer.
  • Use a quality original or equivalent sensor, because cheap generic ones often have different response curves.
  • Clear the codes, drive one full cycle and check in live data that the reading makes sense.

Technical reference data

  • Approximate resistance: about 3,500 ohms at 0 °C (32 °F), 2,000 to 2,500 ohms at 20 °C (68 °F) and about 300 ohms at 80 °C (176 °F).
  • Approximate signal voltage: 3 to 3.5 V with air at 20 °C (68 °F), dropping as it warms up.
  • Computer reference: 5 V.
  • Open circuit reading on the scan tool: about -40 °C (-40 °F). Short circuit reading: more than 120 °C (248 °F).
  • Values are approximate, so check the manufacturer data for your engine.

Brand-specific notes

When you see a P0111 code on a turbocharged engine, remember there is usually a second sensor after the intercooler, with its own code.

P0111 on Ford

On many Ford vehicles the IAT is built into the MAF and is not sold separately. If the fault is in the sensor, you replace the whole assembly.

P0111 on GM

On many GM vehicles the IAT is built into the MAF and is not sold separately. If the fault is in the sensor, you replace the whole assembly.

P0111 on Nissan

On many Nissan vehicles the IAT is built into the MAF and is not sold separately. If the fault is in the sensor, you replace the whole assembly.

P0111 on Toyota

On many Toyota vehicles the IAT is built into the MAF and is not sold separately. If the fault is in the sensor, you replace the whole assembly.

Frequently asked questions about P0111

Can I drive with a P0111 code?
Yes. In general there is no immediate risk, but the engine runs on a substitute value and may use more fuel. Get it repaired soon.
Does the P0111 code always mean replacing the IAT sensor?
No. In most cases the fault is in the connector or the wiring. Do the power, ground and continuity tests first.
What is the difference between low signal and high signal?
On a thermistor, a low signal means an impossibly high temperature (a short circuit) and a high signal means an impossibly low temperature (an open circuit).
How much does it cost to fix P0111?
Roughly $15 to $150. The cheapest repair is fixing a connector and the most expensive is replacing the sensor with labor. It varies by shop and region.
What does the P0111 code mean?
It is a generic OBD2 code that means the intake air temperature reading is electrically valid but not believable next to the other sensors. The sensor may read wrong or be stuck.
Will a P0111 code clear itself?
Only if the cause was temporary, such as a real condition that has gone away. If the sensor is out of calibration or slow, the computer will set the code again and you will need to repair it.

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