AutoCodes – Generic – U2105

U2105 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 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 16,933

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

What does this mean?

What are the Possible Causes of the DTC U2105?

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?

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 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 U2105 code?

Need more information on how to fix the U2105 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U2105 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U2105 Buick — Lost Communications with Engine Control Module
U2105 Cadillac — Lost Communications with Engine Control Module
U2105 Chevrolet — Lost Communications with Engine Control Module
U2105 GMC — Lost Communications with Engine Control Module
U2105 Saturn — Lost Communications with Engine Control Module

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 Code

1. What are common symptoms of the OBDII code U2105 (Lost Communications with Engine Control Module)?

- Common symptoms include engine stalling, rough idling, poor acceleration, and the check engine light being illuminated.

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

- Possible causes include faulty wiring or connections, a malfunctioning Engine Control Module (ECM), a damaged CAN bus network, or a software issue.

3. How can I diagnose the U2105 code?

- Diagnosing the U2105 code involves checking the wiring and connectors for any visible damage, testing the ECM for functionality, and using a diagnostic scan tool to communicate with the ECM.

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

- Repair tips include repairing or replacing any damaged wiring or connectors, resetting the ECM, updating the ECM software, or replacing the ECM if necessary.

5. Can I drive my vehicle with the U2105 code?

- It is not recommended to drive your vehicle with the U2105 code present, as it can lead to further damage or safety issues. It is best to address the issue promptly.

6. How do I reset the U2105 code?

- You can reset the U2105 code using a diagnostic scan tool by clearing the code after addressing the underlying issue that triggered it.

7. Is the U2105 code a serious issue?

- The U2105 code can be a serious issue as it affects communication with the ECM, which can impact the performance and drivability of the vehicle.

8. Can a DIY enthusiast fix the U2105 code?

- Depending on your level of automotive knowledge and experience, you may be able to address the U2105 code yourself by checking connections, wiring, and performing basic diagnostic steps.

9. How long does it take to repair the U2105 code?

- The time to repair the U2105 code can vary depending on the underlying cause. It may take anywhere from a few minutes to several hours, especially if extensive diagnostics or part replacement is needed.

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

- The cost to repair the U2105 code can vary based on the cause of the issue and the necessary repairs. Costs may range from a simple fix with minimal expenses to more significant repairs that could be costly.