P0071
UniversalAmbient Air Temperature Sensor Range/Performance
Low SeverityThe Ambient Air Temperature Sensor measures the outside air temperature, which is used by the Engine Control Module for various calculations including fuel mixture and air conditioning operation. When this sensor provides an out-of-range or inconsistent signal, the vehicle's climate control and engine performance may be slightly affected, although it rarely leads to significant drivability issues.
⚠️ Before You Begin (Safety First)
Always wear appropriate personal protective equipment, such as safety glasses and gloves, when working on a vehicle. Ensure the vehicle is parked on a level surface and the ignition is off before performing any repairs. Be careful when handling electrical components. Disconnect the battery before working on electrical systems to prevent electrical shock or damage to components.
Common Symptoms
- Check Engine Light illuminated
- Incorrect outside temperature reading on the dashboard display
- Malfunctioning climate control system (e.g., A/C not blowing cold air, heater not working correctly)
- Slightly reduced fuel efficiency (less common)
- Poor engine performance (very rare and usually subtle)
Common Causes
- Faulty Ambient Air Temperature (AAT) sensor
- Corroded or damaged wiring or connectors to the AAT sensor
- Open or short circuit in the AAT sensor wiring harness
- Engine Control Module (ECM) failure (rare)
- Sensor obstructed or improperly mounted
Frequently reported on: General/Universal
Diagnostic Steps
- Visually inspect the Ambient Air Temperature Sensor and its wiring for any obvious signs of damage, corrosion, or disconnections. The sensor is typically located in front of the radiator, behind the grille, or in the front bumper area.
- Disconnect the sensor connector and check for bent pins or corrosion. Clean any corrosion using electrical contact cleaner.
- Using a multimeter, check the resistance of the sensor (if specifications are available) and the voltage at the connector to ensure it is receiving proper power and ground.
- If the sensor or wiring appears damaged, replace the faulty component.
- Clear the P0071 code using an OBD-II scanner and test drive the vehicle to see if the code returns.
👨🔧 When to Call a Professional
While often a simple DIY fix, if you're unable to locate the sensor, diagnose wiring issues, or the code persists after replacing the sensor, it's best to consult a professional mechanic. This could indicate a deeper electrical problem or an issue with the Engine Control Module itself.
Commonly Asked Questions
What does a P0071 code mean?
The P0071 code indicates that your vehicle's computer has detected an issue with the signal from the Ambient Air Temperature Sensor, meaning the sensor's reading is out of its expected range or performing inconsistently.
Can I drive with a P0071 code?
Yes, generally you can drive with a P0071 code. It typically doesn't cause severe drivability issues, though your climate control might not function correctly, and the dash temperature display might be inaccurate.
Where is the Ambient Air Temperature Sensor located?
The sensor is commonly located at the front of the vehicle, often behind the grille, in the front bumper, or near the radiator support, where it can get an accurate reading of the outside air.
How do I test the Ambient Air Temperature Sensor?
You can test the sensor using a multimeter to check its resistance, which should change with temperature. You can also check for proper voltage supply to the sensor connector. Consult your vehicle's repair manual for specific resistance values.
Will replacing the sensor fix the P0071 code?
In many cases, yes, replacing a faulty Ambient Air Temperature Sensor will resolve the P0071 code. However, if the issue is with the wiring or the Engine Control Module, replacing the sensor alone will not fix the problem.