AutoCodes – GMC – U0020 2015 GMC Sierra

U0020 2015 GMC Sierra Code - Low Speed CAN Bus

Quick Answer

Devices connected to the General Motors Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include If other codes are present, diagnose other codes first, Faulty Control Module, Control Module harness is open or shorted. 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
U0020 2015 GMC Sierra indicates Low Speed CAN Bus.
Common causes
Common causes include If other codes are present, diagnose other codes first, Faulty Control Module, Control Module harness is open or shorted.
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.
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Code Popularity 349
How popular is this code, among other codes? Low
Table of contents Created and updated by William Orellana on Jul 19, 2023
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Code U0020 2015 GMC Sierra Description

Devices connected to the General Motors Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages need to be exchanged on the serial data circuits. The messages are also supervised, and some periodic messages are used by the receiver device as an availability indication of the transmitter device. The Diagnostic Trouble Code (DTC) will be set when a supervised periodic message that includes the transmitter device availability has not been received.
OBDII Code U0020 2015 GMC Sierra - Low Speed CAN Bus - AutoCodes.com
U0020 2015 GMC Sierra Code - Low Speed CAN Bus

What are the Possible Causes of the DTC U0020 2015 GMC Sierra?

  • If other codes are present, diagnose other codes first
  • Faulty Control Module
  • Control Module harness is open or shorted
  • Control Module circuit poor electrical connection

How to Fix the DTC U0020 2015 GMC Sierra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

Code Tech Notes

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U0020 2015 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the U0020 2015 GMC Sierra code?

Need more information on how to fix the U0020 2015 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

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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 U0020 2015 GMC Sierra Code

1. What does the OBDII code U0020 for a 2015 GMC Sierra indicate?

The U0020 code specifically refers to a fault in the Low Speed Controller Area Network (CAN) Bus communication system of the vehicle.

2. What are common symptoms of a U0020 code in a 2015 GMC Sierra?

Common symptoms include issues with the vehicle's communication network, such as problems with various electronic components like the instrument cluster, powertrain control module, or body control module.

3. What are potential causes of a U0020 code in a 2015 GMC Sierra?

Potential causes can include damaged wiring, loose connections, faulty modules, or issues with the CAN bus network itself.

4. How can I diagnose a U0020 code in my 2015 GMC Sierra?

Diagnosing a U0020 code typically involves using a professional OBDII scanner to retrieve the specific details of the fault, checking for any loose connections or damaged wiring in the CAN bus system, and testing the various modules for proper function.

5. Can I still drive my 2015 GMC Sierra with a U0020 code present?

It is not recommended to drive the vehicle with a U0020 code present, as it can lead to further issues with the vehicle's electronic systems and potentially affect its overall performance and safety.

6. How can I repair a U0020 code in my 2015 GMC Sierra?

Repairing a U0020 code may involve fixing any damaged wiring, securing loose connections, replacing faulty modules, or resetting the CAN bus system using a professional diagnostic tool.

7. Is it necessary to reset the U0020 code after repairs?

Yes, it is important to clear the U0020 code from the vehicle's system after making any necessary repairs to ensure that the issue has been resolved and to prevent any further warnings or malfunctions.

8. Can a DIY enthusiast fix a U0020 code in a 2015 GMC Sierra?

While some basic troubleshooting steps can be taken by a DIY enthusiast, diagnosing and repairing a U0020 code often requires specialized knowledge and tools, so it is recommended to seek professional help for accurate diagnosis and repair.

9. Are there any preventive measures to avoid a U0020 code in a 2015 GMC Sierra?

Regular maintenance of the vehicle's electrical system, checking for any signs of wear or damage in the wiring, and addressing any communication issues promptly can help prevent the occurrence of a U0020 code.

10. How much does it typically cost to repair a U0020 code in a 2015 GMC Sierra?

The cost of repairing a U0020 code can vary depending on the specific underlying issue, the extent of the repairs needed, and the labor rates of the repair shop. It is advisable to obtain quotes from different service providers for an accurate estimate.

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