P0111: The intake air temperature reading does not agree with what other sensors suggest

Intake air temperature (IAT) sensor range/performance problem

Severity: Monitor

An intake air temperature sensor that reads off is a sensor fault to fix at your convenience; TroubleCodes.net lists no hazardous effects for it.

Source: how we rate severity

P0111 in short

P0111 means the intake air temperature sensor reading is out of line with what the computer expects, judged against other sensors such as coolant temperature. A failed or contaminated sensor, a sensor touching metal, or damaged wiring are the usual causes. Check the sensor and its wiring before replacing anything.

The intake air temperature (IAT) sensor tells the engine computer how warm the incoming air is. P0111 is a range or performance code: the signal is present, but it does not make sense compared with other readings such as engine coolant temperature.

TroubleCodes.net lists a defective sensor, a sensor contaminated by a dirty air filter or heavy PCV blow-by, a sensor installed so that it touches metal, and rodent-damaged wiring on stored cars.

Its three-step approach is to measure the sensor's resistance against a temperature chart, check the circuit voltage, and use scan-tool live data to compare readings with the sensor connected and unplugged.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

Cause 1: Defective intake air temperature sensor
Common general cause
Why it ranks here
TroubleCodes.net lists a defective sensor from manufacturing or damage first.
What would change this
A sensor whose resistance does not follow the temperature chart raises it.
How to test the intake air temperature (iat) sensor
Cause 2: Sensor contaminated by a dirty air filter or PCV blow-by
Common general cause
Why it ranks here
The page lists contamination from dirty air filters or excessive PCV blow-by.
What would change this
Oil or dirt coating the sensor raises it.
How to test the intake air temperature (iat) sensor
Cause 3: Sensor touching metal or improperly installed
Possible — needs testing
Why it ranks here
The page lists improper installation where the sensor contacts metal surfaces, which would bias its reading.
What would change this
A sensor found touching metal raises it.
How to test the intake air temperature (iat) sensor
Cause 4: Damaged wiring, including rodent damage on stored vehicles
Possible — needs testing
Why it ranks here
Wiring damage on stored vehicles is listed.
What would change this
Chewed or corroded wiring, or wrong circuit voltage, raises it.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

Step 1: Measure the sensor's resistance at a known temperature and compare it with the resistance chart for your vehicle.
Low riskTool: digital multimeter
- IfResistance does not match the chart
  It meansThe sensor is at fault.
  Points to: Defective intake air temperature sensor
- IfResistance matches the chart
  It meansCheck the circuit voltages.
  Go to step 2
Step 2: With the key on and engine off, check for a 5 volt reference on one wire and a good ground on the other.
Low riskTool: digital multimeter
- IfReference or ground is missing or low
  It meansThe wiring or connector is at fault.
  Points to: Damaged wiring, including rodent damage on stored vehicles
- IfVoltages are correct
  It meansCompare live readings next.
  Go to step 3
Step 3: With a scan tool, compare the IAT reading with the sensor connected and then unplugged.
Low riskTool: scan tool with live data
- IfThe reading changes when the sensor is unplugged
  It meansThe sensor is the likely problem.
  Points to: Defective intake air temperature sensor
- IfThe reading does not change
  It meansA circuit problem is more likely.
  Points to: Damaged wiring, including rodent damage on stored vehicles

Symptoms

Check engine light

How to fix

Step 1: Look at the IAT sensor and its connector for dirt, oil, damage or contact with metal.

Parts and cost context

Intake air temperature (IAT) sensor:On many engines the sensor is part of the MAF sensor. Test it before replacing it. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

We don't have reviewed vehicle-specific evidence for P0111 yet. The causes and tests above apply across vehicles.

No curated relationships for P0111 yet.

All Air metering (MAF, MAP and intake air temperature) codes

P0111 questions

What does range/performance mean for P0111?

The sensor signal exists but does not match what other sensors, such as coolant temperature, suggest it should be.

Sources and review

P0111 code page — TroubleCodes.net
On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles

Last reviewed: October 16, 2026
Written by: Saurabh K.
Editorial review: Pending
Technician review: Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

Severity: Monitor

Most likely causes

Cause 1: Defective intake air temperature sensor

Cause 2: Sensor contaminated by a dirty air filter or PCV blow-by

Cause 3: Sensor touching metal or improperly installed

Cause 4: Damaged wiring, including rodent damage on stored vehicles

What to test first

Step 1: Measure the sensor's resistance at a known temperature and compare it with the resistance chart for your vehicle.

Step 2: With the key on and engine off, check for a 5 volt reference on one wire and a good ground on the other.

Step 3: With a scan tool, compare the IAT reading with the sensor connected and then unplugged.