AutoCodes – Generic – U240B

U240B Code - Radio Dedicated Bus Off

Quick Answer

The high-speed General Motors Local Area Network (GMLAN) serial data circuits are serial data buses used to communicate information between the devices. Common causes include Faulty Radio, Radio harness is open or shorted, Radio 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: U240B indicates Radio Dedicated Bus Off.
Common causes: Common causes include Faulty Radio, Radio harness is open or shorted, Radio 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 797

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 17, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U240B Description

The high-speed General Motors Local Area Network (GMLAN) serial data circuits are serial data buses used to communicate information between the devices. The high-speed GMLAN serial data circuits also connect directly to the X84 Data Link Connector (DLC) for programming purposes. If this serial data system is inoperative, some devices may still be able to communicate with the scan tool due to other serial data systems but not with each other. The device setting the Diagnostic Trouble Code (DTC) has attempted to establish communications on the high-speed GMLAN serial data circuits more than 3 times.

OBDII Code U240B - Radio Dedicated Bus Off - AutoCodes.com — U240B Code - Radio Dedicated Bus Off

What does this mean?

What are the Possible Causes of the DTC U240B?

Faulty Radio
Radio harness is open or shorted
Radio circuit poor electrical connection

How to Fix the DTC U240B?

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 U240B 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 U240B code?

Need more information on how to fix the U240B code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U240B code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U240B Buick — Radio Dedicated Bus Off
U240B Cadillac — Radio Dedicated Bus Off
U240B Chevrolet — Radio Dedicated Bus Off
U240B GMC — Radio Dedicated Bus Off

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 U240B Code

1. What are the common symptoms of OBDII code U240B, Radio Dedicated Bus Off?

- Common symptoms include the radio not working, no sound from the speakers, and loss of communication with the radio control module.

2. What are possible causes of the U240B code, Radio Dedicated Bus Off?

- Possible causes include a faulty radio control module, wiring issues in the radio bus circuit, or a communication error with the vehicle's main computer.

3. How can I diagnose the U240B code related to the Radio Dedicated Bus Off issue?

- Diagnose the code by checking the radio control module for faults, inspecting the wiring for any damage, and using a diagnostic tool to communicate with the module.

4. Can a DIY enthusiast repair the U240B code, Radio Dedicated Bus Off?

- Repairing the code may require advanced knowledge and tools, so it is recommended to consult a professional mechanic for proper diagnosis and repair.

5. Are there any temporary fixes for the U240B code, Radio Dedicated Bus Off?

- Temporary fixes like resetting the radio system by disconnecting the battery may sometimes resolve the issue, but it is important to address the root cause for a permanent solution.

6. Is it safe to continue driving with the U240B code, Radio Dedicated Bus Off?

- While driving with this code may not pose an immediate safety risk, it is best to address the problem promptly to avoid any potential issues with the vehicle's electrical system.

7. How much does it typically cost to repair the U240B code, Radio Dedicated Bus Off?

- Repair costs can vary depending on the cause of the issue, but it is advisable to budget for diagnostic fees, parts replacement, and labor costs when seeking professional repair services.

8. Can a dead battery trigger the U240B code, Radio Dedicated Bus Off?

- Yes, a dead or disconnected battery can sometimes lead to communication errors between modules, including triggering the U240B code related to the radio bus system.

9. Will disconnecting the radio control module reset the U240B code, Radio Dedicated Bus Off?

- Disconnecting the radio control module may reset the code temporarily, but it is crucial to address the underlying issue to prevent the code from reoccurring.

10. How long does it usually take to repair the U240B code, Radio Dedicated Bus Off?

- Repair times can vary depending on the complexity of the issue, availability of parts, and the mechanic's workload, so it is best to consult with a professional for an accurate estimate.