AutoCodes – GMC – U0028 2018 GMC Sierra

U0028 2018 GMC Sierra Code - Media Oriented Systems Transport Bus

Quick Answer

The Media Oriented Systems Transport (MOST) bus consists of a physical ring in which multimedia devices share audio, video and infotainment system control data. Common causes include Faulty Audio Unit (Radio), Audio Unit harness is open or shorted, Audio Unit circuit poor electrical connection. 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: U0028 2018 GMC Sierra indicates Media Oriented Systems Transport Bus.
Common causes: Common causes include Faulty Audio Unit (Radio), Audio Unit harness is open or shorted, Audio Unit circuit poor electrical connection.
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 282

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
Cost to Diagnose
FAQs
Comments
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Code U0028 2018 GMC Sierra Description

The Media Oriented Systems Transport (MOST) bus consists of a physical ring in which multimedia devices share audio, video and infotainment system control data. Each device on the MOST bus transmits and receives data via the MOST Bus Serial Data (+/- transmit/receive) circuits. The MOST bus diagnostic master is the Radio. The MOST control circuit is connected to each device on the MOST bus. Each device provides a 12 V signal on the MOST control circuit. The Radio initiates communication on the MOST bus at Ignition ON by toggling the MOST control circuit low for 100 ms. Once each device recognizes the wakeup signal from the Radio on the MOST control circuit, they will respond to the Radio on the MOST bus to indicate no faults are present and normal communications will commence. The Diagnostic Trouble Code (DTC) sets when a fault occurs on transmit, receive, electronic control lines, or internal device failure.

OBDII Code U0028 2018 GMC Sierra - Media Oriented Systems Transport Bus - AutoCodes.com — U0028 2018 GMC Sierra Code - Media Oriented Systems Transport Bus

What does this mean?

What are the Possible Causes of the DTC U0028 2018 GMC Sierra?

Faulty Audio Unit (Radio)
Audio Unit harness is open or shorted
Audio Unit circuit poor electrical connection

How to Fix the DTC U0028 2018 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U0028 2018 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.

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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 U0028 2018 GMC Sierra Code

1. What does the OBDII code U0028 mean on a 2018 GMC Sierra?

U0028 refers to an issue with the Media Oriented Systems Transport (MOST) bus, indicating a communication fault between electronic control modules on the bus.

2. What are the symptoms of the U0028 code on a 2018 GMC Sierra?

Common symptoms include non-functional or intermittent infotainment system, radio issues, navigation problems, or no audio output.

3. What causes the U0028 code on a 2018 GMC Sierra?

The code can be triggered by a faulty module on the MOST bus, damaged wiring, loose connections, or software glitches.

4. Can a blown fuse cause the U0028 code?

Yes, a blown fuse for the infotainment or communication system can disrupt the MOST bus and trigger this code.

5. How do you diagnose the U0028 code on a 2018 GMC Sierra?

Diagnosis involves scanning for related codes, checking the MOST bus connections, inspecting wiring for damage, and verifying module functionality.

6. Can the U0028 code be cleared without repairs?

Clearing the code might work temporarily, but if the underlying issue isn't fixed, the code will likely return.

7. Is a software update needed to fix the U0028 code?

In some cases, a software update for the affected module may resolve communication issues causing the code.

8. How much does it cost to repair the U0028 code on a 2018 GMC Sierra?

Repair costs vary depending on the issue but can range from $100 for minor wiring fixes to $1,000 or more if a module replacement is needed.

9. Can a U0028 code affect vehicle performance?

This code primarily impacts the infotainment system and does not typically affect core vehicle performance.

10. Can I drive my 2018 GMC Sierra with the U0028 code active?

Yes, the vehicle is generally drivable, but infotainment features like radio or navigation may not work properly.

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