P0071 Fault Code

P0071 OBD-II Trouble Code Short Description

Ambient Air Temperature Sensor Range/Performance

What does trouble code P0071 mean?

P0071 is a diagnostic trouble code that indicates a Range/Performance issue with the Ambient Air Temperature (AAT) sensor. The AAT sensor is responsible for measuring the temperature of the air outside the vehicle and providing this information to the engine control module (ECM).

When the ECM receives a signal from the AAT sensor that is outside the expected range or does not match the other sensor readings, it triggers the P0071 code. This could be caused by a faulty AAT sensor, wiring issues, or a problem with the ECM itself.

If you encounter a P0071 code, it is important to address the issue promptly. Ignoring this code could lead to potential engine performance problems or reduced fuel efficiency.

To diagnose and fix this issue, you can follow these steps:

  1. Inspect the AAT sensor and its wiring for any signs of damage, corrosion, or loose connections. Repair or replace any faulty components.

  2. Use a multimeter to test the resistance of the AAT sensor. Compare the readings with the specifications outlined in the vehicle's service manual. Replace the sensor if it is out of range.

  3. Check the power and ground connections for the AAT sensor. Make sure they are secure and free from any corrosion.

  4. If the AAT sensor and its wiring are both in good condition, the issue may lie with the ECM. In this case, it may be necessary to have the ECM reprogrammed or replaced by a qualified technician.

Remember, it is always recommended to consult the vehicle's service manual or seek assistance from a professional mechanic to ensure an accurate diagnosis and proper repair.


What are the symptoms of the P0071 code?

The P0071 fault code typically indicates a problem with the ambient air temperature (AAT) sensor. Symptoms commonly associated with this code include:

  • Incorrect or erratic temperature readings on the vehicle's display
  • Fluctuating or inaccurate readings from the AAT sensor
  • Illumination of the check engine light (CEL) or malfunction indicator lamp (MIL)
  • Decreased fuel efficiency or performance issues
  • Difficulty starting the engine in extreme temperature conditions

It is important to note that these symptoms may vary depending on the specific vehicle make and model.


What causes the P0071 code?

The P0071 fault code indicates an issue with the Ambient Air Temperature (AAT) sensor. The possible causes of this fault code include:

  1. Faulty AAT sensor: The sensor may be malfunctioning, providing incorrect temperature readings or no readings at all.

  2. Wiring issues: There may be a problem with the wiring or connector associated with the AAT sensor. This could include broken wires, loose connections, or corroded terminals.

  3. Sensor location: If the AAT sensor is located in an area where it is exposed to excessive heat, cold, or external factors, it may affect its performance and trigger the fault code.

  4. Engine control module (ECM) malfunction: In some cases, the fault may be due to an issue with the ECM, which could affect the reading and interpretation of the AAT sensor data.

To diagnose and resolve the P0071 fault code, it is recommended to:

  1. Inspect the AAT sensor and wiring: Ensure that the sensor is securely connected and that there are no visible signs of damage or corrosion.

  2. Test the AAT sensor: Use a multimeter or specialized diagnostic tool to check the resistance and voltage readings of the AAT sensor. Compare the results with the manufacturer's specifications to verify its accuracy.

  3. Verify the sensor location: Make sure that the AAT sensor is installed in the correct location, away from any possible sources of interference or extreme temperatures.

  4. Check the ECM: If all else fails, it may be necessary to inspect the ECM for any potential malfunctions or errors. This task is best left to a professional mechanic or dealer technician.

By identifying and addressing the root cause of the P0071 fault code, you can ensure that the AAT sensor is functioning properly and accurately reporting the ambient air temperature to the vehicle's ECM.

Possible Solutions

How to fix P0071?

To fix the P0071 fault code on cars related to the Ambient Air Temperature Sensor Range/Performance, you can follow these steps:

  1. Inspect the sensor: Check if the sensor is properly connected and free from any visible damage or corrosion. Clean the sensor if necessary.

  2. Test the sensor: Use a multimeter to measure the resistance of the sensor at different temperatures. Consult the car's repair manual for the specific resistance values expected for your vehicle.

  3. Replace the sensor: If the sensor is found to be faulty or if its resistance values are outside the acceptable range, replace the sensor with a new one. Ensure that you purchase a genuine or high-quality replacement.

  4. Check the wiring: Inspect the wiring and connectors for any visible damage or loose connections. Repair or replace any damaged wiring as needed.

  5. Clear the fault codes: After replacing the sensor or fixing any wiring issues, use an OBD-II scanner to clear the fault codes from the car's computer. This will reset the system and allow the car to relearn the new sensor or wiring.

Note: If you are unsure about any step or lack the necessary tools and experience, it is advisable to seek professional assistance from a certified mechanic.