AutoCodes – GMC – U0020 2017 GMC Sierra

U0020 2017 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 2017 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 244

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 19, 2023

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code U0020 2017 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 2017 GMC Sierra - Low Speed CAN Bus - AutoCodes.com — U0020 2017 GMC Sierra Code - Low Speed CAN Bus

What does this mean?

What are the Possible Causes of the DTC U0020 2017 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 2017 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.

What does this mean?

Code Tech Notes

Controller Area Network (CAN)

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U0020 2017 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 2017 GMC Sierra 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 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.