Ambient Air Temperature Sensor Range/Performance
P0071 indicates the Ambient Air Temperature (AAT) sensor is not performing within expected parameters. The PCM has detected a signal that is out of range, disconnected, or shorted, preventing accurate outside temperature readings.
What You Might Notice
- Malfunction Indicator Light (Check Engine) illuminated
- Air conditioning system may not function properly
- Instrument cluster fails to display outside temperature
- Overhead console temperature display inaccurate or blank
- Climate control may default to manual operation only
Most Common Causes
- 1
Open circuit in AAT sensor wiring
A broken or disconnected wire in the signal circuit to the ambient air temperature sensor prevents the PCM from receiving a signal.
- 2
Faulty AAT sensor
The ambient air temperature sensor itself has failed and is no longer providing accurate temperature readings to the PCM.
- 3
Short to voltage in signal circuit
The AAT sensor signal wire is shorted to a positive voltage source, causing an out-of-range high signal that the PCM cannot interpret correctly.
- 4
Short to ground in signal circuit
The AAT sensor signal wire is grounded improperly, causing the PCM to read an invalid or minimum temperature signal.
How to Diagnose It
- 1
Check Open circuit in AAT sensor wiring — A broken or disconnected wire in the signal circuit to the ambient air temperature sensor prevents the PCM from receiving a signal.
- 2
Check Faulty AAT sensor — The ambient air temperature sensor itself has failed and is no longer providing accurate temperature readings to the PCM.
- 3
Check Short to voltage in signal circuit — The AAT sensor signal wire is shorted to a positive voltage source, causing an out-of-range high signal that the PCM cannot interpret correctly.
- 4
Check Short to ground in signal circuit — The AAT sensor signal wire is grounded improperly, causing the PCM to read an invalid or minimum temperature signal.
How to Fix It
- 1
Inspect and repair AAT sensor wiring
Locate the AAT sensor wiring harness, typically found in the front bumper or grille area. Check for cuts, corrosion, or loose connectors. Repair or replace damaged wiring and ensure proper connections.
- 2
Replace the AAT sensor
Remove the faulty ambient air temperature sensor from its location and install a new OEM or quality replacement sensor. This is the most common fix for P0071 codes.
- 3
Check connector and clean terminals
Disconnect the AAT sensor connector and inspect for corrosion, water intrusion, or damaged pins. Clean with electrical contact cleaner and reconnect firmly, or replace the connector if damaged.
- 4
Verify PCM and reprogram if necessary
If wiring and sensor are confirmed functional, the PCM may require reprogramming or replacement. This is rare but possible if electrical faults have corrupted the module.
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