AutoCodes – GMC – U2105 GMC

U2105 GMC Code - Lost Communications with Engine Control Module

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 Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine Control 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: U2105 GMC indicates Lost Communications with Engine Control Module.
Common causes: Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine Control 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 2,348

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 Apr 18, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U2105 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, and 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 circuit 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 circuits are shorted to battery voltage, ground, or between them no communication is possible on the CAN serial data bus, a DTC will be set.

OBDII Code U2105 GMC - Lost Communications with Engine Control Module - AutoCodes.com — U2105 GMC Code - Lost Communications with Engine Control Module

What does this mean?

What are the Possible Causes of the DTC U2105 GMC?

Faulty Engine Control Module (ECM)
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection

How to Fix the DTC U2105 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 U2105 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.

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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 U2105 GMC Code

1. What are the common symptoms of OBDII code U2105 GMC?

- Common symptoms include engine stalling, rough idling, loss of power, and issues with starting the vehicle.

2. What are the possible causes of the U2105 GMC code?

- The code U2105 typically indicates a communication problem between modules, such as a faulty Engine Control Module (ECM), wiring issues, or a defective CAN bus system.

3. How can I diagnose the U2105 code?

- Diagnosing the U2105 code usually involves using a scan tool to retrieve the specific details of the code and checking the ECM for any communication errors.

4. What are some tips for repairing the U2105 code?

- Some repair tips include checking and repairing any damaged wiring, ensuring all connections are secure, resetting the ECM, or replacing the ECM if necessary.

5. Can a DIY enthusiast fix the U2105 code?

- While some basic troubleshooting steps can be performed by a DIY enthusiast, diagnosing and repairing the U2105 code may require advanced diagnostic tools and expertise, so it's recommended to consult a professional mechanic.

6. Is it safe to continue driving with the U2105 code present?

- It is not recommended to drive the vehicle with the U2105 code present, as it can lead to further damage and potentially unsafe driving conditions. It's best to address the issue promptly.

7. How much does it typically cost to repair the U2105 code?

- The cost of repairing the U2105 code can vary depending on the underlying cause. It may range from a few hundred dollars for simple fixes like wiring repairs to over a thousand dollars for ECM replacement.

8. Are there any recalls related to the U2105 code in GMC vehicles?

- It's always advisable to check with the manufacturer or authorized service centers for any recalls related to the U2105 code in GMC vehicles, as some issues may be covered under warranty.

9. Can a weak battery cause the U2105 code to appear?

- Yes, a weak or failing battery can sometimes trigger communication errors between modules, leading to the U2105 code. It's recommended to ensure the battery is in good condition during diagnosis.

10. How long does it take to repair the U2105 code in a GMC vehicle?

- The repair time for the U2105 code can vary based on the specific cause and complexity of the issue. Simple fixes may take a few hours, while more involved repairs could require a day or more to complete.