OBD-II trouble code
P0111: Intake Air Temperature Sensor 1 Circuit Range/Performance
SAE J2012 names an in-range intake-air-temperature fault. GM publication 12OBDGS2 flags sensor 1 when, after an 8-hour soak, it disagrees with sensor 2 by more than 20°C and also loses the comparison with coolant temperature.
Quick facts
- System
- Powertrain
- Category
- Sensors / Air Intake
- Severity
- Low severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $120 – $150
- DIY difficulty
- Beginner DIY
Browse every code in P0100–P0199, or start from the full code library.
What does P0111 mean?
P0111 is Intake Air Temperature Sensor 1 Circuit Range/Performance in SAE J2012 APR2002. Section 3 describes range/performance as a circuit that is inside its normal electrical range but is not correct for the current conditions. The signal is not pegged at either stop. That is why a resistance check can pass and this code can still be stored.
GM publication 12OBDGS2, common-section engine diagnostics, describes P0111 as an intake-air sensor stuck in range, judged at startup against a second intake-air sensor and against coolant temperature. The malfunction line is the absolute difference between power-up intake-air temperature and power-up intake-air temperature 2 greater than 20°C, and the absolute difference between power-up coolant temperature and power-up intake-air temperature greater than the absolute difference between power-up coolant temperature and power-up intake-air temperature 2. The soak between this ignition cycle and the last time the engine was running must be greater than 28,800 seconds, which is 8 hours. There must be no active coolant-temperature circuit fault and no active circuit fault on either intake-air sensor. The test runs once at the start of the ignition cycle. It is Type B, two trips.
That test requires a second intake-air sensor. An engine with one intake-air sensor does not run this comparison. Confirm the calibration file is 12OBDGS2 before using the 20°C line. The sheet does not mention an oil film, a dirty air filter, or an infrared thermometer.
The 1999 Ford PCED section 4 list does not include P0111. Its intake-air entries are the low and high self-test codes, 0.2 volt and 4.6 volts. A skewed sensor that stays between those volts will not fail those two Ford tests.
Common causes
- On a calibration that uses the 12OBDGS2 test, intake-air sensor 1 disagreed with sensor 2 by more than 20°C after a soak longer than 8 hours, and also lost the coolant-temperature comparison
- A sensor that is electrically inside the low and high stops, which is why P0112 and P0113 are the codes the test requires to be inactive
- A connector or terminal fault that shifts the reading without opening the circuit, found when the cold-soak comparison fails and the wiring is then measured
- The wrong sensor replaced on an engine that has two intake-air sensors, because the inequality identifies which reading is the outlier
- An air-filter or oil-film story used in place of the soak comparison, which this sheet does not list
Symptoms
- Malfunction indicator lamp with P0111
- On the 12OBDGS2 test, a power-up intake-air reading more than 20°C away from the second intake-air sensor after more than 8 hours off
- Coolant temperature at that same power-up closer to sensor 2 than to sensor 1
- No fail while the engine is already hot, because the test executes once at the beginning of the cycle
- P0112 or P0113 stored, which disables this rationality test on that sheet
Diagnostic steps
- 1.Confirm this calibration runs the 12OBDGS2 comparison and that the engine has intake-air sensor 2. If it does not, stop and use the range test printed for this VIN. The 20°C figure is that sheet.
- 2.The enable is a soak greater than 28,800 seconds. A hot restart will not run the test. Leave the engine off for more than 8 hours, then key on and record power-up intake-air temperature, intake-air temperature 2, and coolant temperature before the engine is started.
- 3.Fail is both of these: sensor 1 and sensor 2 differ by more than 20°C, and coolant temperature is closer to sensor 2 than to sensor 1. The second half of that sentence is what picks sensor 1 as the outlier. If sensor 2 is the one that disagrees with both of the others, this inequality is not the failure the sheet prints.
- 4.If P0112 or P0113 is stored, repair that circuit code first. The rationality test is not enabled while those circuit faults are active.
- 5.With the ignition off, disconnect sensor 1 and measure its resistance against the temperature table in the service information for the ambient temperature you just recorded. The 12OBDGS2 row does not print an ohms value. GRP09's 45 ohms and 163,000 ohms belong to P0112 and P0113 on that other sheet.
- 6.Check the sensor-1 signal and its reference for resistance end to end, ignition off, both ends disconnected. A high-resistance joint can shift a thermistor reading without pinning it.
- 7.Replace sensor 1 only after the soak comparison has identified it and the wiring is in range. Clear the code, soak again for more than 8 hours, and confirm the two intake-air readings and the coolant reading no longer meet the fail inequality. An infrared gun on the intake casting is not this test.
Repair cost
$120 – $150
The soak comparison points at an intake-air temperature sensor, and that sensor is about $120 to $150 installed.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with intake air temperature sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is a beginner-friendly repair. Common hand tools, a free afternoon, and a willingness to follow a procedure are usually enough. The risk of causing a bigger problem is low if you read up on your specific vehicle first.