What Does P0071 Mean?
The ECM has determined that the ambient air temperature (AAT) sensor is reading within the circuit's electrical range but the value does not correlate with expected conditions. For example, the sensor may report a temperature that is significantly different from what the ECM calculates based on intake air temperature, coolant temperature at startup, or historical data. This is a rationality/performance fault, not a hard circuit failure. The driver may notice incorrect outside temperature readings.
Common Causes
30%
Sensor mounted in a location affected by engine heat radiation (heat soak)
25%
Partially degraded sensor reading inaccurately but within electrical limits
20%
Sensor contaminated with road grime, oil, or debris affecting readings
15%
Aftermarket bumper or grille modification restricting airflow to the sensor
10%
Intake air temperature sensor disagreement causing ECM to flag the AAT
Diagnostic Steps
1
Compare the AAT sensor reading to IAT sensor reading after a cold soak (vehicle sitting overnight). Both should be very close to actual ambient temperature. A significant difference (more than 10°F/5°C) identifies the drifted sensor.
2
Check the physical mounting of the AAT sensor. It should be in a location with good ambient airflow, away from engine heat, exhaust, and radiator discharge. If the sensor or bumper has been serviced, it may be incorrectly positioned.
3
Inspect the sensor for contamination. Road grime, oil film, or debris packed around the sensor can insulate it and cause sluggish or inaccurate readings. Clean the sensor and housing.
4
Verify the sensor has not been relocated behind a bumper repair or aftermarket grille that blocks airflow to the sensor. Restricted airflow causes heat soak at idle.
5
Measure the sensor's resistance at a known ambient temperature and compare to the manufacturer's resistance vs. temperature chart. If the resistance is off by more than 10%, replace the sensor.
Estimated Repair Cost
$30 - $200
Parts + labor, varies by vehicle and location
The ECM has determined that the ambient air temperature (AAT) sensor is reading within the circuit's electrical range but the value does not correlate with expected conditions. For example, the sensor may report a temperature that is significantly different from what the ECM calculates based on inta...
The most common cause of P0071 (Ambient Air Temperature Sensor Range/Performance) is: Sensor mounted in a location affected by engine heat radiation (heat soak)
Typical repair costs for P0071 range from $30 to $200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. This is a performance/rationality code, not a hard failure. The ECM is receiving a plausible but incorrect temperature value. Impact on engine management is minimal. Climate control temperature display will be inaccurate. Repair at your convenience.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0071 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Engine Management / Climate Control
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
