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P0073 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


Problem in the Ambient Air Temperature (AAT) sensor or the circuit


The error code (DTC) P0073 appears when there is a problem with your vehicle's ambient temperature sensors or its wired circuit. This error code is directly related to your vehicle's internal environment and temperature. Many vehicles and devices are calibrated to self-control and maintain the internal environment. The car's central mainframe computer records the values of Ambient Air Temperature (AAT) sensors and then maintains the internal airflow. The power control module (PCM) will start showing the error code P0073 when the air temperatures exceed the limit of intake air temperature.

 Moreover, the AAT sensors measure and record temperatures of external air and the vehicle’s engine coolant. The external air temperature is interpreted by AAT sensors, which is converted into electrical signals, and then transmitted to the car's PCM system. After getting the data set, both the PCM and CCM integrate to regulate automatic climatic control operations. The readings of the ambient air temperature are visible on the dashboard. 

The error code (DTC) P0073 is detected when the readings and temperatures recorded by AAT sensors are above the normal range. If the recorded temperature exceeds the normal range, PCM triggers warnings on the car's central computer. 


Error code (DTC) P0073 is just like the other OBD-II codes, which pop up when there is a problem in your car's sensors, circuits, and PCM. If you aspire to have a smooth drive, you need to evaluate the error's root cause. Listed below are some potential reasons which might have triggered the error code P0073.

  • Malfunctioned Ambient Air Temperature (AAT) sensors 
  • A problem in the primary circuit and wiring of the AAT sensors
  • Software or hardware issue in the mainframe control module 
  • Dirt and debris might have accumulated on the sensory points
  • Harness damage in AAT sensor or its circuit
  • Malfunctioned PCM, which is most unlikely


While you are driving the car and the engine malfunction light illuminates. You might experience multiple problems simultaneously that may be caused due to the occurrence of error code (DTC) P0073. Mentioned below are the few symptoms that the driver can experience: 

  • Insufficient air supply by Air Conditioning system
  • Warm and suffocated internal environment
  • Fluctuated readings on the instrument cluster
  • Faulty reading showed by the overhead console
  • Failed CCM startup



As a layman and the vehicle's owner, you will be notified when your engine check light illuminates. It is imperative to diagnose the problem and find its root      cause. Moreover, you can start by going through your vehicle's user manual, which contains all causes of error codes and how they can be rectified. 

  • Check for the circuit and wiring of the sensors
  • Check whether your engine is heating 
  • Ensure your radiator hasn't burst or affected the AAT sensors
  • Scan through the engine’s wiring and look for burnt connections and wiring
  • Ensure that the connectors are in place and free from any carbon or soot
  • Try applying electrical grease if it helps in your situation

A mechanic or a qualified motor technician would carry out a detailed diagnosis of the error code P0073. He would be using multiple methods to examine your vehicle and diagnose the root problem.

  • The mechanic would start scanning by freezing the PCM data and analyzing the data using an OBD-II scanner. 
  • The mechanic would closely inspect the wiring, circuits, and the breaker connected to the AAT sensors. Where required, he would replace and repair the damages and coil the openings.
  • After a detailed inspection, the mechanic would do a test run to check whether the PCM detects the error code P0073.
  • If the error code reoccurs and affects the car's ability to function smoothly, the mechanic might replace the ambient air temperature (AAT) sensors.
  • After inspecting and replacing all wired connections and sensors, if the problem prevails, there might be a malfunction in the PCM.
  • The mechanic would examine every reading and voltage value represented in the main dashboard to search for the fault.

Common Mistakes

Not every individual is professional at diagnosing the problems caused by error code P0073.  It is observed that many technicians and mechanics prefer changing the AAT sensors before examining their parallel circuits and wiring. The replacement of AAT sensors isn't the ideal solution; it is advisable to look for minor defects in the circuit and the connectors. A professional mechanic would always look for minor flaws and potential circuit breaks before replacing the AAT sensors.

How Serious is This?

The DTC P0073 error code directly affects your vehicle's air conditioning and heating systems. However, the error code P0073 doesn't affect your car's transmission system and its drive. It would directly affect the smooth working of your car's CCM, which is responsible for maintaining the internal air environment. The driver and other passengers might feel uncomfortable as the air-conditioning system will not work to its actual potential.

What Repairs Can Fix the Code

Regular service and tuning of your car's engine would keep your AAT sensors clean and free from accumulated carbon and debris particles. It is advisable to check your car's engine and sensors that cause error code problems like this.

Related Codes

Other codes related to error code P0073 are:

  • P0070: AAT Sensor Circuit 
  • P0071: AAT Sensor Range or Performance
  • P0072: AART Sensor Low Circuit Input


With timely maintenance and tuning of your car's engine, you can avoid error codes like this in the future. With advancements in technology and the car's engine system, the AAT sensors are specially designed to work under any uncertain condition. However, it is imperative to understand the potential causes of error code P0073 and how it can be avoided in the long run.