AutoCodes – GMC – U18B9 2016 GMC Sierra

U18B9 2016 GMC Sierra Code - Primary High Speed CAN Bus Subnet Configuration List

Quick Answer

The devices on the high-speed General Motor Local Area Network (GMLAN) serial data bus and the chassis high-speed GMLAN serial data bus must be programmed with software that specifically identifies the correct type and quantity of devices on the bus based on RPO configuration. Common causes include Faulty Module that is not configured, Module harness is open or shorted, Module 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: U18B9 2016 GMC Sierra indicates Primary High Speed CAN Bus Subnet Configuration List.
Common causes: Common causes include Faulty Module that is not configured, Module harness is open or shorted, Module 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 171

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 24, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U18B9 2016 GMC Sierra Description

The devices on the high-speed General Motor Local Area Network (GMLAN) serial data bus and the chassis high-speed GMLAN serial data bus must be programmed with software that specifically identifies the correct type and quantity of devices on the bus based on RPO configuration. If a device was not properly configured after installation, the appropriate U Code may be set for that device. No external circuit diagnosis is involved. The Diagnostic Trouble Code (DTC) will set when the device is not configured properly, or the device recognizes a programming error.

OBDII Code U18B9 2016 GMC Sierra - Primary High Speed CAN Bus Subnet Configuration List - AutoCodes.com — U18B9 2016 GMC Sierra Code - Primary High Speed CAN Bus Subnet Configuration List

What does this mean?

What are the Possible Causes of the DTC U18B9 2016 GMC Sierra?

Faulty Module that is not configured
Module harness is open or shorted
Module circuit poor electrical connection

How to Fix the DTC U18B9 2016 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 U18B9 2016 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 U18B9 2016 GMC Sierra code?

Need more information on how to fix the U18B9 2016 GMC Sierra code? Get Access to Factory Service Manuals

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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 U18B9 2016 GMC Sierra Code

1. What does the OBDII code U18B9 mean on a 2016 GMC Sierra?

The U18B9 code indicates an issue with the Primary High-Speed CAN Bus Subnet Configuration List, meaning there may be communication errors between control modules on the high-speed CAN bus network.

2. What are the common symptoms of the U18B9 code in a 2016 GMC Sierra?

Symptoms may include warning lights on the dashboard, loss of communication with certain control modules, erratic vehicle behavior, or performance issues.

3. What causes the U18B9 code on a GMC Sierra?

The code can be caused by faulty wiring, loose or damaged CAN bus connectors, a failed control module, or software issues requiring reprogramming.

4. How can I diagnose the U18B9 code in my 2016 GMC Sierra?

Use a scan tool to check for related codes and monitor CAN bus communication. Inspect the wiring and connectors for damage or corrosion, and verify that no modules are malfunctioning.

5. Can a faulty battery cause the U18B9 code on a 2016 GMC Sierra?

Yes, low battery voltage or poor battery connections can disrupt communication on the CAN bus network and trigger the U18B9 code.

6. Is the U18B9 code serious for my 2016 GMC Sierra?

While the vehicle may still be drivable, the code can indicate underlying communication issues that could lead to further problems, so it should be addressed promptly.

7. What is the repair process for the U18B9 code in a GMC Sierra?

Repairs may include fixing or replacing damaged wiring or connectors, reprogramming or replacing faulty modules, and ensuring proper voltage levels in the electrical system.

8. Can I clear the U18B9 code without fixing the issue?

You can clear the code with a scan tool, but if the root cause isnâ€™t resolved, the code and symptoms will likely return.

9. Which modules are typically involved in the U18B9 code on a 2016 GMC Sierra?

Modules on the high-speed CAN bus, such as the engine control module (ECM), transmission control module (TCM), or body control module (BCM), may be involved.

10. How much does it cost to fix the U18B9 code on a 2016 GMC Sierra?

The cost depends on the root cause, ranging from $100 for simple wiring repairs to $1,000 or more if module replacement is required.