What it means
The control module detects an ambient air temperature reading outside the expected range or performance limits.
At a glance
- Usually lights the check-engine light
How it works
Ambient air temperature sensor A measures outside air temperature, which the control module uses for temperature-related calculations and may share with the display or climate system. P0071 sets when its reading is outside the expected range or changes in a way the module considers implausible, including from heat exposure or a sensor that has drifted.
Common causes
Most likely first.
- Sensor reading drifted
- Sensor exposed to engine heat
- Sensor element aged beyond calibration window
Symptoms
- Check-engine light on
- Outside-temperature display may be inaccurate
- Automatic climate control may behave unexpectedly
How to diagnose it
- Compare the live sensor A reading with actual ambient conditions after the vehicle has sat long enough for the sensor to cool.
- Check freeze-frame data to see whether the fault occurred after hot engine operation or in unusual conditions.
- Inspect sensor A's position and nearby parts for heat exposure, and check its connector for corrosion or poor contact.
- Inspect the wiring for damage, then monitor whether the reading changes smoothly as conditions change.
- Test sensor A and its circuit against the manufacturer's specification before replacing it.
Common fixes
- Restore the sensor to its correct position if it has been displaced near a heat source.
- Repair a loose, corroded, or damaged sensor A connector.
- Repair damaged wiring that causes an implausible reading.
- Replace sensor A if it has drifted outside the manufacturer's specification.
Can I keep driving?
This code generally does not prevent normal driving, but the outside temperature display and automatic climate control may be inaccurate. Have it checked when convenient, especially if climate control behavior is distracting or uncomfortable.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.