AutoCodes – GMC – U18B9 2017 GMC Sierra

U18B9 2017 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 2017 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 181

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 2017 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 2017 GMC Sierra - Primary High Speed CAN Bus Subnet Configuration List - AutoCodes.com — U18B9 2017 GMC Sierra Code - Primary High Speed CAN Bus Subnet Configuration List

What does this mean?

What are the Possible Causes of the DTC U18B9 2017 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 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U18B9 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 U18B9 2017 GMC Sierra code?

Need more information on how to fix the U18B9 2017 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 2017 GMC Sierra Code

1. What does the OBDII code U18B9 mean for a 2017 GMC Sierra?

The code U18B9 indicates an issue with the Primary High Speed CAN Bus Subnet Configuration List in the vehicle's communication network.

2. What are the common symptoms of a U18B9 fault in a 2017 GMC Sierra?

Common symptoms may include communication errors between various control modules, intermittent or complete loss of certain vehicle functions, and warning lights on the dashboard.

3. What are the possible causes of a U18B9 code in a 2017 GMC Sierra?

Possible causes include damaged wiring or connectors in the CAN bus system, faulty control modules, software issues, or a malfunctioning gateway module.

4. How can I diagnose a U18B9 fault in my 2017 GMC Sierra?

Diagnosis typically involves using a diagnostic scanner to retrieve the trouble code, checking the CAN bus network for faults, inspecting wiring and connectors for damage, and testing control modules for proper communication.

5. Can I drive my 2017 GMC Sierra with a U18B9 fault code?

It is not recommended to drive the vehicle with an unresolved U18B9 code, as it may lead to further electrical issues and potentially affect the vehicle's performance and safety.

6. How can I repair a U18B9 fault in my 2017 GMC Sierra?

Repairing a U18B9 fault may involve repairing or replacing damaged wiring or connectors, reprogramming control modules, or replacing faulty components identified during diagnosis.

7. Can a DIY enthusiast fix a U18B9 fault in a 2017 GMC Sierra?

While basic troubleshooting like checking connectors and wiring can be done by DIY enthusiasts, addressing complex issues related to the CAN bus system may require specialized equipment and expertise.

8. Are there any recalls or service bulletins related to the U18B9 code in a 2017 GMC Sierra?

It's recommended to check with the manufacturer or a GMC dealership for any recalls or service bulletins related to the U18B9 fault in your specific vehicle.

9. How much does it typically cost to repair a U18B9 fault in a 2017 GMC Sierra?

The cost of repairing a U18B9 fault can vary depending on the underlying cause, the extent of the repairs needed, and labor rates at the repair facility.

10. How can I prevent a U18B9 fault from occurring in my 2017 GMC Sierra?

To prevent a U18B9 fault, it's important to perform regular maintenance on your vehicle, address any electrical issues promptly, and avoid tampering with the vehicle's wiring or control modules unless necessary.