U0073 code: Control module communication bus A off solution


One of the most common problems with your vehicle is this U0073 trouble code. Many people don’t know the details of this problem. Let’s see every detail of this problem:

What do you mean by the U0073 code?

The primary meaning of the U0073 is “control module communication bus “A” off.” This code stands for Diagnostic Trouble Code (DTC). This code is pervasive in every vehicle. This code is mainly seen when your car loses total control of the control module. That’s why the communication system diagnostic code is connected to the CAN bus of U0073. This code relates to the PCM, anti-lock braking system (ABS), TCM, body control module, etc.

  • Two network speed modes:

All of the modules in your car are just connected, like the nerve system of the human body. The standard vehicle has 40 modules. But you will also find more than 40 modules in another car. This module is a switch embedded that is used to send a switch signal utilizing the network of some modules. There are two types of networks on this bus: CAN high and CAN low. In addition, there are two network speed modes: one for one-wire networks and two for two-wire networks. This module is used as a translator. This receives input from many networks; these modules also send the information and data.

But the most exciting part of this U0073 code is that it doesn’t seem applicable to all-new cars or vehicles, so this code is applied to the old type of vehicle, which requires the fastest network in the CAN bus, which has different speeds. As a result, the CAN bus speed is also critical for the information and data users expect to receive.

  • For old vehicles

The fastest CAN bus is usually used for sensitive work like vehicle dynamics, power training, etc. Nowadays, the engine control module (ECM) and transmission control module (PCM) are separate from each other, and they are concentrated in just a single powertrain control module. Additional information also passes through the modules between these two parts on average driving time. This is a setup for the old-type vehicle. In the modern one, the bevy of Uxxx used to see the problem.

Possible cause of U0073 fault code:

There are multiple reasons you found to create this problem. Like: U0073 Control Module Communication Bus A Off

  1. Problem with any control module,
  2.  A loose or broken wire, poor connection problem,
  3. The problem with the data network. 

Reason for this U0073 Code:

No problem happens without any reason. Like that, the U0073 also has some reasons to create problems. Like:

  1. Engine power loss or sudden stop working while driving,
  2. The engine light is illuminated,
  3. No crank condition is possible,
  4. Economically fuel is reduced,
  5. The driver’s information message is displayed on the monitor,
  6. Data transmission shift problem,
  7. All indicators of the cluster display “ON.”

These are the primary reasons for this U0073 problem. When you see this code, you can quickly know why this type of problem.

Diagnosis of the problem of code U0073:

To diagnose the problem of the code U0073, need some steps to follow:

  1. The battery must be fully charged, and all connections must be correctly hard and clean.
  2. Now it’s time to use the scan tool to read the fault stored in DTC memory. Take the value and compare it with manufacturer-specific diagnostic codes.
  3. For confirmation, use another scan tool in all modules of CAN bus A.
  4. It needs to verify all modules to see if they can communicate correctly with each other or not. It gives the best result if it takes time to drive.
  5.  You need to run the troubleshooting in every component to see if it fails or has some similar problem in the same type of components from another car or vehicle. The ECM configures the problem identically with the exact VIN.
  6. When the ECM is replaced successfully, then clear all previous code. Now take the vehicle for a test drive to ensure it’s ready or not.how to fix u0073 code

Some common mistakes you made in the diagnosis of the U0073 problem:

The code U0073 is related to the control module problem. So making a mistake also takes you to the road of risk. Some common errors everyone faces determine the difficulty of this code. Like:

  1. Using only one computer for diagnosis,
  2. Run the troubleshooting system that stops working for other reasons,
  3. Reference points were collected from the old DTC of the vehicle.
  4. Replace or repair the part of the vehicle without confirming the module compatibility from the specification list.
  5. Without notice, the problem of plugging or unplugging the connector.
  6. Remove the faulty component from poor communication with CAN bus “A.”
  7. Taking a long time to notice the problem and solve it.
  8. Ignore the problem of transmission or engine speed sensor or O2 sensor during driving,
  9. Not seeing the analog gauges in the testing time,
  10. Replace or repair random parts without fixing the problem,
  11. Bypass some essential step-like, like voltage level check or resistance, etc.

So before running any diagnosis, please don’t make this mistake and follow every small step.

How to fix trouble code U0073?

Some easy steps can get rid of this problem. They are:

  1. If the PCM, ECM module, or control unit fails to detect the problem, replace it.
  2. Faulty high or low CAN buses also need to be replaced,
  3. Re-flush the total vehicle module, and if it needs, flush the program also.
  4. At some time to complete the total power train of every component, we need to replace the faulty sensor. And this step needs to communicate properly again after that.

The necessity to solve the problem of code U0073:

The U0073 code of the OBD 2 scanner is related to a control module. So you can imagine the seriousness of this problem to be solved. The solving process is also complicated to fix the issue, and it takes more time than usual. Sometimes, one or two modules need to be changed. So try to do it immediately. And after changing it, take the vehicle on a test drive to ensure the problem is fully solved or not. And you need to spend some money to solve this problem. It needs about $100-$1000 to fix the problem.

More OBD2 Error Codes: U0001, U0002

Kevin Nicholas is an automotive technician who is a genius at software and hardware-related issues. He manually tested more than a hundred OBD scanners and gave his honest opinion on whether the device was worth the money or not. His in-depth OBD review articles help people choose the right product, whether it is a European, American, or Asian vehicle. He completed his Automotive Specialized Training Course at Universal Technical Institute and has more than 15 years of experience in the field.

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