AutoCodes – Buick – U18B4 Buick

U18B4 Buick Code - Lost Communication With Radio On Ethernet Bus

Quick Answer

At the core of the infotainment system is the Radio Ethernet Audio Video Bridging switch which communicates directly to each contributing Infotainment control module terminator. 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: U18B4 Buick indicates Lost Communication With Radio On Ethernet Bus.
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 988

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 08, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U18B4 Buick Description

At the core of the infotainment system is the Radio Ethernet Audio Video Bridging switch which communicates directly to each contributing Infotainment control module terminator. The Ethernet harness consists of twisted pair wires from point to point. Each control module on the Ethernet infotainment system sends/receives data at 100 Mbit/s to/from a specified port at the Radio. The Radio Ethernet will also be used to program USB software update files to the control modules connected to the Ethernet ports. The Diagnostic Trouble Code (DTC) will set a supervised periodic message that includes the transmitter device availability that has not been received.

OBDII Code U18B4 Buick - Lost Communication With Radio On Ethernet Bus - AutoCodes.com — U18B4 Buick Code - Lost Communication With Radio On Ethernet Bus

What does this mean?

What are the Possible Causes of the DTC U18B4 Buick?

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

How to Fix the DTC U18B4 Buick?

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 U18B4 Buick 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 U18B4 Buick code?

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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 U18B4 Buick Code

1. What does OBDII code U18B4 mean on a Buick?

It indicates a loss of communication with the radio module over the Ethernet bus, typically pointing to a connectivity or wiring issue.

2. What are the common symptoms of code U18B4 in a Buick?

Symptoms may include a non-functional or unresponsive radio, lack of audio output, and possible disruptions in related infotainment or Bluetooth systems.

3. What causes the U18B4 code to appear?

Common causes include faulty wiring, a malfunctioning radio module, issues with the Ethernet communication bus, or a software glitch in the control modules.

4. Can a blown fuse cause the U18B4 code?

Yes, a blown fuse related to the radio or infotainment system can interrupt communication on the Ethernet bus and trigger this code.

5. How can I diagnose the U18B4 code on my Buick?

Start by inspecting the wiring and connectors to the radio module, checking for physical damage or loose connections. Use a scan tool to verify communication with the radio module and related systems.

6. Is the U18B4 code related to other vehicle systems?

Yes, it can affect systems that rely on the radio module, such as navigation, Bluetooth, and voice recognition features.

7. Can I drive my Buick with the U18B4 code active?

Yes, the vehicle can still be driven, but you may experience functionality issues with the infotainment system.

8. How do I fix the U18B4 code in my Buick?

Repairs may involve reconnecting or repairing damaged wiring, replacing a faulty radio module, or performing a software update on the affected modules.

9. Does the U18B4 code require a radio replacement?

Not always. It could be resolved with wiring repairs, software updates, or a reset. Only replace the radio module if itâ€™s confirmed as the faulty component.

10. Will clearing the code fix the U18B4 issue?

Clearing the code may temporarily reset the system, but the underlying issue must be addressed to prevent the code from returning.