Engine-CodesGMC – U0020 2017 GMC Sierra

U0020 2017 GMC Sierra Code - Low Speed CAN Bus

Quick Answer

The U0020 code for a 2017 GMC Sierra indicates a problem with the Low Speed Controller Area Network (CAN) Bus. Common causes include Faulty module connected to the Low Speed CAN Bus, Wiring harness damage or corrosion, Loose or poor connections in the CAN Bus network. 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 2017 GMC Sierra indicates Low Speed CAN Bus.
Common causes
Common causes include Faulty module connected to the Low Speed CAN Bus, Wiring harness damage or corrosion, Loose or poor connections in the CAN Bus network.
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 13, 2024
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Code U0020 2017 GMC Sierra Description

The U0020 code for a 2017 GMC Sierra indicates a problem with the Low Speed Controller Area Network (CAN) Bus. The CAN Bus is a communication network that allows various modules in the vehicle to communicate with each other. The Low Speed CAN Bus specifically deals with communication between modules at lower speeds, typically for non-critical systems such as interior lighting, power windows, and door locks.

OBDII Code U0020 2017 GMC Sierra - Low Speed CAN Bus
U0020 2017 GMC Sierra Code - Low Speed CAN Bus

Common Causes of U0020 2017 GMC Sierra

  1. Faulty module connected to the Low Speed CAN Bus
  2. Wiring harness damage or corrosion
  3. Loose or poor connections in the CAN Bus network
  4. Software glitch in one of the modules
  5. Water damage to the vehicle's electrical system

Symptoms of U0020 2017 GMC Sierra

  1. Power windows not functioning properly
  2. Interior lights flickering or not working
  3. Door locks not responding to the remote key fob
  4. Issues with the radio or infotainment system
  5. Dashboard warning lights related to communication errors

How to Fix U0020 2017 GMC Sierra

  1. Perform a thorough diagnostic scan to retrieve the specific module causing the communication issue.
  2. Inspect the wiring harness for any damage or corrosion, repairing or replacing as needed.
  3. Check all connections in the Low Speed CAN Bus network and ensure they are secure.
  4. Update software in the affected modules to address any glitches.
  5. Clear the U0020 code from the vehicle's computer and test the systems to ensure proper communication is restored.

Cost to Fix U0020 2017 GMC Sierra

The typical repair costs for addressing a U0020 code in a 2017 GMC Sierra can range from $200 to $500, depending on the exact cause of the issue and the labor rates at the auto repair shop. This estimate includes parts and labor. It's important to note that diagnosis time and labor rates can vary, so it's advisable to check with local shops for a more accurate estimate. Keep in mind that rates may be higher at dealerships or in metropolitan areas, while independent shops may offer more competitive pricing.

Tech Notes for U0020 2017 GMC Sierra

Controller Area Network (CAN)

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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 2017 GMC Sierra Code

1. What does the OBDII code U0020 on a 2017 GMC Sierra indicate?

The code U0020 on a 2017 GMC Sierra specifically relates to a Low Speed CAN Bus communication problem.

2. What are some common symptoms of a Low Speed CAN Bus issue in a 2017 GMC Sierra?

Common symptoms include dashboard warning lights, erratic behavior of vehicle systems, and potential loss of communication with certain modules.

3. What are potential causes of the U0020 code on a 2017 GMC Sierra?

Causes can include damaged wiring, loose connections, faulty control modules, or issues with the CAN Bus network itself.

4. How can I diagnose a Low Speed CAN Bus problem in my 2017 GMC Sierra?

Diagnosis typically involves checking the wiring harness, inspecting connections, and using a diagnostic scanner to identify the specific location of the communication fault.

5. Can a DIY enthusiast repair a U0020 code on a 2017 GMC Sierra?

While basic checks like inspecting connections can be done by DIY enthusiasts, diagnosing and repairing complex CAN Bus issues may require professional assistance.

6. Is it safe to continue driving my 2017 GMC Sierra with a U0020 code present?

It is not recommended to drive the vehicle with a U0020 code as it can lead to potential safety hazards and further damage to vehicle systems.

7. How much does it typically cost to repair a Low Speed CAN Bus issue on a 2017 GMC Sierra?

The cost of repair can vary depending on the exact cause of the issue, but it may range from a few hundred to a few thousand dollars, including parts and labor.

8. Can a U0020 code on a 2017 GMC Sierra be related to other underlying problems?

Yes, a U0020 code can sometimes be triggered by underlying issues such as water damage, electrical faults, or even software malfunctions.

9. Will resetting the OBDII code U0020 on a 2017 GMC Sierra make the problem go away?

Resetting the code may temporarily clear the warning light, but if the underlying issue causing the U0020 code is not addressed, it is likely to reoccur.

10. How can I prevent a U0020 code from appearing on my 2017 GMC Sierra in the future?

Regular vehicle maintenance, avoiding water exposure, and addressing any electrical problems promptly can help prevent the recurrence of a U0020 code.

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