AutoCodes – Buick – U1147 Buick

U1147 Buick Code - Lost Communication With Onstar

Quick Answer

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Common causes include Faulty Onstar, Onstar harness is open or shorted, Onstar 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: U1147 Buick indicates Lost Communication With Onstar.
Common causes: Common causes include Faulty Onstar, Onstar harness is open or shorted, Onstar 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 521

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 24, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1147 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) U1147 is set.

OBDII Code U1147 Buick - Lost Communication With Onstar - AutoCodes.com — U1147 Buick Code - Lost Communication With Onstar

What does this mean?

What are the Possible Causes of the DTC U1147 Buick?

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

How to Fix the DTC U1147 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 U1147 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 U1147 Buick Code

1. What does OBDII code U1147 mean on a Buick?

Code U1147 indicates a loss of communication between the vehicleâ€™s control modules and the OnStar system.

2. What are the common symptoms of code U1147 on a Buick?

Symptoms may include the OnStar system not functioning, warning lights on the dashboard, or intermittent communication issues with other vehicle systems.

3. What causes code U1147 to appear on a Buick?

Common causes include a faulty OnStar module, damaged wiring or connectors, communication bus errors, or software glitches in the vehicleâ€™s control modules.

4. Can I still drive my Buick with code U1147 active?

Yes, code U1147 typically does not affect drivability, but the OnStar system and some connected features may not work properly.

5. How do I diagnose code U1147 on my Buick?

Start by scanning the vehicle for additional codes, inspecting the wiring and connectors related to the OnStar module, and checking for software updates or communication errors.

6. Is a faulty OnStar module the only cause of code U1147?

No, other causes can include wiring issues, problems with the communication bus, or faults in other related control modules.

7. How do I fix code U1147 on a Buick?

Repairs may include replacing a faulty OnStar module, repairing damaged wiring or connectors, or reprogramming control modules if a software update is required.

8. How much does it cost to repair code U1147 on a Buick?

Repair costs vary but may range from $100 for minor wiring repairs to $500 or more if the OnStar module needs replacement.

9. Can I reset code U1147 without fixing the issue?

You can clear the code with a scan tool, but it will likely return if the underlying problem is not addressed.

10. Do I need a professional mechanic to fix code U1147?

While basic diagnostics can be done at home, resolving communication issues often requires specialized tools and expertise, so professional assistance is recommended.