AutoCodesBuick – U1129 Buick

U1129 Buick Code - Lost Communications With Audio Amplifier

Quick Answer

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Common causes include Faulty Audio Amplifier, Audio Amplifier harness is open or shorted, Audio Amplifier 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
U1129 Buick indicates Lost Communications With Audio Amplifier.
Common causes
Common causes include Faulty Audio Amplifier, Audio Amplifier harness is open or shorted, Audio Amplifier 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 441
How popular is this code, among other codes? Low
Table of contents Created and updated by William Orellana on Apr 22, 2020
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Code U1129 Buick Description

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for the state of health monitoring/node alive messages. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an identification number is learned by a module, it will monitor for that module node alive message. Each module on the class 2 serial data circuit is required to send a Node Alive message every 2 seconds. When no message is detected from a learned identification number for 5 seconds, a Diagnostic Trouble Code (DTC) U1129 is set.
OBDII Code U1129 Buick - Lost Communications With Audio Amplifier - AutoCodes.com
U1129 Buick Code - Lost Communications With Audio Amplifier

What are the Possible Causes of the DTC U1129 Buick?

  • Faulty Audio Amplifier
  • Audio Amplifier harness is open or shorted
  • Audio Amplifier circuit poor electrical connection

How to Fix the DTC U1129 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 U1129 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.

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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 U1129 Buick Code

1. What does the OBDII code U1129 mean on a Buick?

The U1129 code indicates that the vehicle's control module has lost communication with the audio amplifier, which is part of the vehicle's communication network.

2. What are the common symptoms of the U1129 code in a Buick?

Common symptoms include a non-functional audio system, distorted or no sound output, and possible warning lights on the dashboard.

3. What causes the U1129 code to appear in a Buick?

The most common causes are a faulty audio amplifier, damaged wiring or connectors in the communication network, or a failing control module.

4. Can a weak battery cause the U1129 code in a Buick?

Yes, a weak or failing battery can cause communication errors like U1129, as insufficient voltage can disrupt the network.

5. How is the U1129 code diagnosed in a Buick?

A technician uses a scan tool to check for communication with the audio amplifier, inspects wiring and connectors, and tests the amplifier for proper operation.

6. Can I still drive my Buick with a U1129 code?

Yes, you can drive the vehicle, but the audio system may not function properly, and the issue may lead to further electrical problems if left unresolved.

7. How do I fix the U1129 code in my Buick?

Repairs may include replacing the audio amplifier, repairing damaged wiring or connectors, or updating/reprogramming the vehicle’s control module.

8. Is the U1129 code specific to Buicks with premium audio systems?

Yes, the code is more likely to occur in Buicks equipped with advanced or premium audio systems that use a separate amplifier.

9. How much does it cost to repair the U1129 code on a Buick?

The cost can vary, but replacing an audio amplifier typically ranges from $300 to $800, with additional costs for diagnostics or wiring repairs.

10. Can a software update fix the U1129 code in a Buick?

In some cases, a software update to the control module may resolve communication issues if the problem is related to outdated firmware.

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