Engine-CodesGMC – U0073 GMC

U0073 GMC Code - Control Module Communication Bus OFF

Quick Answer

The U0073 GMC code indicates that there is a communication bus off between one or more control modules in the vehicle. Common causes include Faulty Wiring: Damaged or corroded wiring can disrupt the communication between control modules, Defective Control Module: A malfunctioning control module can prevent proper communication with other modules, Software Glitch: A software glitch in one of the control modules can cause a breakdown in communication. 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 GMC indicates Control Module Communication Bus OFF.
Common causes
Common causes include Faulty Wiring: Damaged or corroded wiring can disrupt the communication between control modules, Defective Control Module: A malfunctioning control module can prevent proper communication with other modules, Software Glitch: A software glitch in one of the control modules can cause a breakdown in communication.
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.
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code U0073 GMC Description

The U0073 GMC code indicates that there is a communication bus off between one or more control modules in the vehicle. Control modules are electronic components that communicate with each other to ensure the proper functioning of various systems in the vehicle, such as the engine, transmission, ABS, and airbags. When the communication bus is off, it means that there is a disruption in the network, leading to a loss of communication between the modules. This can result in the vehicle's systems not working correctly or at all, potentially causing safety hazards or performance issues.

OBDII Code U0073 GMC - Control Module Communication Bus OFF
U0073 GMC Code - Control Module Communication Bus OFF

Common Causes of U0073 GMC

  1. Faulty Wiring: Damaged or corroded wiring can disrupt the communication between control modules.
  2. Defective Control Module: A malfunctioning control module can prevent proper communication with other modules.
  3. Software Glitch: A software glitch in one of the control modules can cause a breakdown in communication.
  4. Battery or Charging System Issue: A weak or failing battery or charging system can lead to voltage fluctuations that affect the communication bus.
  5. Water Intrusion: Water entering the vehicle's electrical system can cause corrosion and disrupt communication between modules.

Symptoms of U0073 GMC

  1. Check Engine Light: The most common symptom associated with the U0073 code is the illumination of the check engine light on the vehicle's dashboard.
  2. Loss of Communication: The driver may experience a loss of communication between various systems in the vehicle, leading to malfunctions or erratic behavior.
  3. Reduced Performance: The vehicle may exhibit reduced performance, such as rough idling, poor acceleration, or difficulty shifting gears.
  4. Inoperative Systems: Certain systems in the vehicle, such as the ABS, airbags, or traction control, may not function correctly or at all.
  5. Limp Mode: In severe cases, the vehicle may go into a limp mode, restricting power and speed to prevent further damage.

How to Fix U0073 GMC

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the trouble codes and perform a thorough inspection of the vehicle's wiring, connections, and control modules to identify the root cause of the communication bus off condition.
  2. Repair or Replace Wiring: Repair or replace any damaged or corroded wiring that is causing the communication issue.
  3. Test Control Modules: Test each control module to determine if any are faulty and need to be replaced.
  4. Update Software: If a software glitch is identified as the cause, update the affected control module's software to resolve the issue.
  5. Check Battery and Charging System: Test the vehicle's battery and charging system to ensure they are functioning properly and providing stable voltage to the control modules.

Cost to Fix U0073 GMC

The typical repair costs for addressing a U0073 GMC code can vary depending on the specific cause of the communication bus off condition. On average, the repair costs can range from $200 to $500, including parts and labor. However, it's essential to note that the actual cost may be higher or lower based on factors such as the location of the repair shop, the vehicle's make and model, and the extent of the repairs needed. Additionally, diagnosis time and labor rates at auto repair shops can vary, with hourly rates typically ranging between $80 and $150. It's advisable to consult with a professional technician to get a more accurate estimate based on your specific situation.

Tech Notes for U0073 GMC

There is a factory service bulletin for the following GMC models:
2007-2010 GMC Sierra
2007-2010 GMC Yukon Models
2008-2010 GMC Sierra Hybrid
2008-2010 GMC Yukon Hybrid
GMC Factory Service Bulletin OBDII Code U0073





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Information for Specific GMC Models

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 GMC Code

1. What does the OBDII code U0073 mean on a GMC vehicle?

The U0073 code indicates a problem with the Control Module Communication Bus, typically caused by a loss of communication between control modules.

2. What are the common symptoms of code U0073 in a GMC?

Symptoms may include a check engine light, other warning lights, failure of certain vehicle functions, or the vehicle not starting.

3. What causes the U0073 code to appear in GMC vehicles?

Common causes include a faulty control module, damaged wiring, poor electrical connections, or issues with the Controller Area Network (CAN) bus.

4. Can a weak battery cause the U0073 code in a GMC?

Yes, a weak or failing battery can disrupt communication between modules and trigger the U0073 code.

5. How do I diagnose the U0073 code on my GMC?

Use an advanced OBDII scanner to check for additional communication-related codes, inspect wiring and connectors for damage, and test the battery and control modules.

6. Is it safe to drive with the U0073 code on a GMC vehicle?

It depends on the severity of the issue. If critical systems are affected, it may be unsafe to drive until the problem is resolved.

7. What is the first step in fixing code U0073 on a GMC?

Start by checking the battery voltage, inspecting the CAN bus wiring, and ensuring all module connectors are secure.

8. Can a damaged CAN bus cause the U0073 code?

Yes, a damaged or shorted CAN bus can prevent communication between control modules and trigger the code.

9. Do I need to replace a control module to fix the U0073 code on a GMC?

Not always. The issue might be related to wiring, connectors, or power supply, so these should be checked before replacing a module.

10. How much does it cost to repair a U0073 code on a GMC?

The cost varies depending on the root cause, but repairs could range from $100 for simple wiring fixes to over $1,000 for module replacement.

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