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Engine-Codes – Generic – U0073

U0073 Code - Control Module Communication Bus 'A' Off

Quick Answer

The U0073 code indicates that the Control Module Communication Bus 'A' is not functioning properly or is currently offline. Common causes include Damaged wiring or connectors in the communication bus circuit, Faulty control module, Software glitches or errors. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
U0073 indicates Control Module Communication Bus 'A' Off.
Common causes
Common causes include Damaged wiring or connectors in the communication bus circuit, Faulty control module, Software glitches or errors.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 06, 2024
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Code U0073 Description

The U0073 code indicates that the Control Module Communication Bus 'A' is not functioning properly or is currently offline. This communication bus is responsible for transmitting data between various control modules within the vehicle, such as the engine control module, transmission control module, anti-lock brake system, and others. When this communication bus is not operational, it can lead to a loss of communication between these modules, resulting in a variety of issues with the vehicle's performance and functionality.

OBDII Code U0073 - Control Module Communication Bus 'A' Off
U0073 Code - Control Module Communication Bus 'A' Off

Common Causes of U0073

  1. Damaged wiring or connectors in the communication bus circuit
  2. Faulty control module
  3. Software glitches or errors
  4. Water intrusion causing corrosion in the system

Symptoms of U0073

  1. Engine starting issues
  2. Rough idling or stalling
  3. Transmission shifting problems
  4. Warning lights illuminated on the dashboard
  5. Loss of communication with various control modules

How to Fix U0073

  1. Diagnose the specific cause of the communication bus failure using a diagnostic scanner.
  2. Inspect the wiring and connectors for any signs of damage or corrosion and repair or replace as necessary.
  3. Check the control modules for faults and replace any that are malfunctioning.
  4. Update the software in the affected modules to ensure compatibility and proper communication.
  5. Clear the trouble codes, reset the system, and test drive the vehicle to verify that the issue has been resolved.

Cost to Fix U0073

The typical repair costs for addressing the U0073 code can vary depending on the specific cause of the issue and the extent of the repairs needed. In general, the cost of parts and labor for this repair can range from $200 to $500. However, it's important to note that the actual cost may be higher or lower based on factors such as the location of the repair shop, the make and model of the vehicle, and the expertise of the technician. It's recommended to obtain quotes from multiple repair shops to compare prices and ensure a fair and accurate estimate.

What does this mean?

Tech Notes for U0073

When there are problems with the way different systems in a vehicle communicate with each other using a technology called Controller Area Network (CAN) communication, Diagnostic Trouble Codes (DTC) are displayed. These codes can be caused by issues with the main bus or branch of the communication network, or with the Electronic Control Units (ECUs) and sensors that make up the different systems. If you see code for both the CAN communication problems and internal or power source problems at the same time, you should focus on fixing the internal or power source problems first.





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Code U0073 Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about U0073 Code

1. What does the OBDII code U0073 mean?

The U0073 code indicates that there is a communication issue on the Control Module Communication Bus 'A,' which is part of the vehicle's Controller Area Network (CAN).

2. What are the common symptoms of code U0073?

Symptoms may include a check engine light, erratic or non-functioning electronic systems, failure of certain modules to communicate, or the vehicle entering limp mode.

3. What causes the U0073 code to appear?

Common causes include a faulty control module, damaged CAN wiring, poor electrical connections, low battery voltage, or issues with the CAN bus network.

4. How is the U0073 code diagnosed?

Technicians use a scan tool to check for additional codes, inspect the CAN bus wiring and connectors for damage, and test the voltage and resistance in the communication circuit.

5. Can a weak battery cause the U0073 code?

Yes, a weak or failing battery can result in low voltage, which may disrupt module communication and trigger the U0073 code.

6. Can I still drive my car with the U0073 code?

Driving with the U0073 code is not recommended, as it may cause critical systems to malfunction or the vehicle to enter limp mode.

7. How is code U0073 fixed?

Repairs may include replacing or repairing damaged wiring, ensuring proper connections, reprogramming or replacing a faulty control module, or addressing battery and voltage issues.

8. Can a loose connector cause the U0073 code?

Yes, a loose or corroded connector in the CAN bus circuit can disrupt communication and trigger the U0073 code.

9. Is the U0073 code specific to one control module?

No, the U0073 code refers to a general communication issue on the CAN bus and may involve multiple control modules.

10. How much does it cost to fix the U0073 code?

The repair cost depends on the issue. Simple fixes like repairing wiring or connectors may cost $100–$300, while replacing a control module can exceed $1,000.

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