P0072 Fault Code

Ambient Air Temperature Sensor Circuit Low Input

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0072 fault code refers to a problem with the ambient air temperature sensor circuit. This sensor is responsible for measuring the temperature of the air outside the vehicle and providing that information to the engine control module (ECM).

When the ECM detects a low input from the ambient air temperature sensor circuit, it means that the sensor is not providing the expected voltage or resistance readings. This can be caused by a few different issues, including:

1. Faulty sensor: The ambient air temperature sensor may be defective or damaged, resulting in inaccurate readings or no readings at all. In this case, replacing the sensor should solve the problem.

2. Wiring or connection issues: There may be a problem with the wiring or connections between the sensor and the ECM. Damage or corrosion in the wires, loose connections, or a short circuit can all cause a low input. Checking and repairing any damaged wiring or connections can fix the issue.

3. ECM malfunction: In rare cases, the issue may lie with the ECM itself. If all other potential causes have been ruled out, the ECM should be inspected and potentially replaced.

To diagnose and repair the P0072 fault code, it is recommended to follow these steps:

1. Use an OBD-II scanner to retrieve the trouble codes and check for any other related codes that may give additional clues.

2. Inspect the ambient air temperature sensor and its wiring for any visible damage.

3. Test the sensor's voltage or resistance using a multimeter to determine if it is functioning properly.

4. Check the wiring and connections between the sensor and the ECM for any issues.

5. Clear the fault codes from the ECM memory after making any repairs to see if the issue has been resolved.

In summary, the P0072 fault code indicates a low input from the ambient air temperature sensor circuit. The sensor, wiring, and connections should be inspected and repaired if necessary, and the ECM may need to be replaced in rare cases.

What are the symptoms of the P0072 code?

The P0072 fault code indicates a low input in the circuit of the Ambient Air Temperature (AAT) sensor in the car. This can manifest with the following symptoms:

• The AAT sensor reading on the dashboard may be inaccurate or show unrealistic values.
• The vehicle's automatic climate control system may not function correctly, leading to incorrect temperature settings.
• The engine may have difficulty starting, or may hesitate during acceleration.
• The fuel efficiency of the vehicle may decrease.
• The Check Engine Light (CEL) may illuminate on the dashboard.

If you experience any of these symptoms, it is recommended to have your vehicle diagnosed and repaired by a qualified mechanic to resolve the P0072 fault code.

What causes the P0072 code?

The P0072 fault code on cars indicates a problem with the Ambient Air Temperature Sensor Circuit Low Input. This means that the sensor's signal voltage is lower than the specified range. Several factors can cause this fault code, including:

1. Faulty Ambient Air Temperature Sensor: The sensor may be defective or damaged, resulting in inaccurate temperature readings.

2. Wiring or Connection Issues: A damaged or corroded sensor connector, loose wiring, or a short circuit can cause a low input voltage.

3. Open or Grounded Circuit: If the circuit is open or grounded, it can affect the sensor signal and trigger the fault code.

4. PCM or ECM Malfunction: The Powertrain Control Module (PCM) or Engine Control Module (ECM) may be faulty, causing the incorrect interpretation of the sensor's input.

5. Environmental Factors: Extreme temperature conditions or exposure to water, dirt, or debris can affect the sensor's functionality and trigger a low input voltage.

To diagnose and resolve the P0072 fault code, it is recommended to:

• Inspect the wiring and connections for any visible damage or corrosion.
• Check the sensor's resistance and compare it to the manufacturer's specifications.
• Test the sensor signal voltage using a multimeter or diagnostic tool.
• Ensure there are no open or grounded circuits in the sensor's circuitry.
• Inspect the PCM or ECM for any signs of malfunction or fault codes related to temperature sensors.
• If necessary, replace the faulty sensor or repair any wiring or connection issues.

Remember to consult the specific vehicle's repair manual or seek professional assistance for accurate diagnosis and repair.

How to fix P0072?

To fix the P0072 fault code on cars, you can try the following steps:

1. Check the ambient air temperature sensor: Inspect the sensor for any damage or loose connections. Clean the sensor to remove any dirt or debris that may be causing a faulty reading.

2. Test the sensor's resistance: Use a multimeter to measure the resistance of the ambient air temperature sensor. Compare the reading with the manufacturer's specifications. If the resistance is outside of the acceptable range, replace the sensor.

3. Verify the wiring and connectors: Inspect the wiring and connectors related to the ambient air temperature sensor. Look for any signs of damage, corrosion, or loose connections. Repair or replace any faulty wiring or connectors.

4. Reset the fault code: After performing the necessary repairs, clear the fault code using an OBD-II scanner or by disconnecting the car's battery for a few minutes. If the fault code returns, further diagnosis may be needed.

Note: These steps are general guidelines and may differ depending on the make and model of your car. It is recommended to consult the vehicle's service manual or seek professional assistance for accurate diagnosis and repair.