AutoCodes – GMC – U2109 GMC

U2109 GMC Code - Lost Communications With Powertrain Multiple Control System

Quick Answer

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Powertrain Multiple Control System, Powertrain Multiple Control System harness is open or shorted, Powertrain Multiple Control System 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: U2109 GMC indicates Lost Communications With Powertrain Multiple Control System.
Common causes: Common causes include Faulty Powertrain Multiple Control System, Powertrain Multiple Control System harness is open or shorted, Powertrain Multiple Control System 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 774

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 Jun 15, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code U2109 GMC Description

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module. A module with a CAN serial data circuits malfunction or which loses power during the current ignition cycle will have a Loss of Communication Diagnostic Trouble Code (DTC) set by other modules that depend on information from that failed module. If any of the CAN circuit are shorted to battery voltage, ground, or between them no communication is possible on the CAN serial data bus, a Diagnostic Trouble Code will set.

OBDII Code U2109 GMC - Lost Communications With Powertrain Multiple Control System - AutoCodes.com — U2109 GMC Code - Lost Communications With Powertrain Multiple Control System

What does this mean?

What are the Possible Causes of the DTC U2109 GMC?

Faulty Powertrain Multiple Control System
Powertrain Multiple Control System harness is open or shorted
Powertrain Multiple Control System circuit poor electrical connection

How to Fix the DTC U2109 GMC?

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 U2109 GMC 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 U2109 GMC code?

Need more information on how to fix the U2109 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U2109 GMC code diagnosed by a professional: Find a repair shop in your area

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 U2109 GMC Code

1. What are the common symptoms of OBDII code U2109 in a GMC vehicle?

- Common symptoms include check engine light illumination, problems with shifting gears, loss of power, and issues with acceleration.

2. What are the possible causes of the U2109 code in a GMC vehicle?

- The U2109 code can be triggered by issues such as damaged wiring, faulty connectors, a malfunctioning powertrain control module (PCM), or a communication network error.

3. How can I diagnose the U2109 code in my GMC vehicle?

- To diagnose the U2109 code, you can use an OBDII scanner to retrieve the trouble codes, inspect the wiring and connectors for damage, and perform a thorough check of the powertrain control module (PCM) and communication network.

4. Can a DIY enthusiast repair the U2109 code issue in a GMC vehicle?

- While some basic troubleshooting steps can be taken by a DIY enthusiast, resolving the U2109 code may require specialized diagnostic tools and expertise. It is recommended to consult a professional mechanic for proper diagnosis and repair.

5. Are there any quick repair tips for fixing the U2109 code in a GMC vehicle?

- Quick repair tips include checking and repairing any damaged wiring or connectors, resetting the PCM, and ensuring all connections are secure. If the issue persists, seek professional assistance.

6. How serious is the U2109 code in a GMC vehicle?

- The U2109 code indicates a communication error with the powertrain control system, which can affect the overall performance and drivability of the vehicle. It is important to address this issue promptly to prevent further damage.

7. Can driving with the U2109 code cause further damage to my GMC vehicle?

- Continuing to drive with the U2109 code may lead to additional issues such as poor fuel efficiency, engine misfires, or even complete powertrain failure. It is advisable to address the problem as soon as possible.

8. How much does it typically cost to repair the U2109 code in a GMC vehicle?

- The cost of repairing the U2109 code can vary depending on the underlying cause of the issue, the extent of the damage, and the labor rates of the repair shop. It is recommended to obtain quotes from multiple mechanics for an accurate estimate.

9. Can the U2109 code be a recurring problem in a GMC vehicle?

- If the root cause of the U2109 code is not properly identified and fixed, it can potentially recur in the future. It is crucial to address all related issues to prevent the code from reappearing.

10. Is it safe to continue driving my GMC vehicle with the U2109 code unresolved?

- It is not recommended to drive your GMC vehicle with the U2109 code unresolved, as it can lead to performance issues and potential safety concerns. It is best to address the problem promptly to ensure the vehicle's reliability.