AutoCodes – GMC – U0020 2014 GMC Sierra

U0020 2014 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 2014 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 317

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 2014 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 2014 GMC Sierra - Low Speed CAN Bus - AutoCodes.com — U0020 2014 GMC Sierra Code - Low Speed CAN Bus

What does this mean?

What are the Possible Causes of the DTC U0020 2014 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 2014 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 2014 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 2014 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 2014 GMC Sierra Code

1. What does the OBDII code U0020 mean on a 2014 GMC Sierra?

The code U0020 indicates a communication issue on the Low-Speed Controller Area Network (CAN) bus, which can disrupt data exchange between various vehicle modules.

2. What are the common symptoms of code U0020 on a 2014 GMC Sierra?

Symptoms may include warning lights on the dashboard, intermittent electrical issues, loss of communication with certain modules, or malfunctioning features like power windows or locks.

3. What causes the U0020 code to appear on a 2014 GMC Sierra?

Common causes include damaged or corroded wiring, a faulty module on the low-speed CAN bus, poor electrical connections, or a failing CAN bus communication line.

4. How can I diagnose the U0020 code on my GMC Sierra?

Start by inspecting the wiring and connectors on the low-speed CAN bus for damage or corrosion. Use a diagnostic scanner to identify which module is not communicating and perform continuity tests on the network wires.

5. Can a dead battery trigger the U0020 code on a 2014 GMC Sierra?

Yes, a dead or weak battery can cause low voltage, disrupting communication on the low-speed CAN bus and triggering the U0020 code.

6. How do I fix the U0020 code on my 2014 GMC Sierra?

Repairs may include fixing or replacing damaged wires, cleaning corroded connectors, replacing a faulty module, or updating module software if necessary.

7. Can I still drive my 2014 GMC Sierra with the U0020 code active?

While the vehicle may still be drivable, ignoring the code can lead to further electrical malfunctions or safety system failures. It's best to address the issue promptly.

8. Which modules are typically affected by the U0020 code on a 2014 GMC Sierra?

Modules connected to the low-speed CAN bus, such as the body control module (BCM), door modules, or HVAC controls, may be affected.

9. How much does it cost to fix the U0020 code on a 2014 GMC Sierra?

Repair costs vary depending on the issue but can range from $50 for a simple wiring fix to $500 or more if a module replacement is required.

10. Can a DIYer fix the U0020 code on a GMC Sierra?

Yes, if you have basic automotive repair skills, a wiring diagram, and access to a diagnostic scanner, you can attempt to diagnose and fix the issue yourself.