AutoCodes – Buick – U172A Buick

U172A Buick Code - Left High Beam Control Module Lost Communication With Left Headlamp Horizontal Motor

Quick Answer

The Local Interconnect Network (LIN) Bus consists of a single wire with a transmission rate of 10.417 Kbit/s. Common causes include Faulty Left Headlamp Horizontal Motor, Left Headlamp Horizontal Motor harness is open or shorted, Left Headlamp Horizontal Motor 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: U172A Buick indicates Left High Beam Control Module Lost Communication With Left Headlamp Horizontal Motor.
Common causes: Common causes include Faulty Left Headlamp Horizontal Motor, Left Headlamp Horizontal Motor harness is open or shorted, Left Headlamp Horizontal Motor 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 540

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jun 07, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U172A Buick Description

The Local Interconnect Network (LIN) Bus consists of a single wire with a transmission rate of 10.417 Kbit/s. The serial data is transmitted over a LIN circuit between a master control module and other LIN devices within a particular subsystem. If serial data communication is lost between any of the LIN devices on the LIN bus network, the master control module will set a no communication code against the non-communicating LIN device. The Diagnostic Trouble Code (DTC) will set when a supervised periodic message to the Left High Beam Control Module from the Left Headlamp Horizontal Motor has not been received.

OBDII Code U172A Buick - Left High Beam Control Module Lost Communication With Left Headlamp Horizontal Motor - AutoCodes.com — U172A Buick Code - Left High Beam Control Module Lost Communication With Left Headlamp Horizontal Motor

What does this mean?

What are the Possible Causes of the DTC U172A Buick?

Faulty Left Headlamp Horizontal Motor
Left Headlamp Horizontal Motor harness is open or shorted
Left Headlamp Horizontal Motor circuit poor electrical connection
Faulty Left High Beam Control Module

How to Fix the DTC U172A 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 U172A 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 U172A Buick Code

1. What does the OBDII code U172A mean on a Buick?

The U172A code indicates that the Left High Beam Control Module has lost communication with the Left Headlamp Horizontal Motor.

2. What are the symptoms of the U172A code on a Buick?

Symptoms may include the left high beam not functioning properly, the headlight not adjusting horizontally, or a warning light on the dashboard.

3. What causes the U172A code to appear on a Buick?

Common causes include faulty wiring or connections, a malfunctioning Left High Beam Control Module, a defective Left Headlamp Horizontal Motor, or software issues.

4. Can I drive my Buick with the U172A code active?

Yes, but the left headlight's high beam or horizontal adjustment may not work, which could compromise visibility and safety, especially at night.

5. How do I diagnose the U172A code on a Buick?

Use a scan tool to confirm the code, inspect the wiring and connectors between the control module and the horizontal motor, and test the functionality of both components.

6. How can I fix the U172A code on my Buick?

Repairs may include reconnecting or replacing damaged wiring, updating the control module's software, or replacing the faulty Left Headlamp Horizontal Motor or Control Module.

7. How much does it cost to fix the U172A code on a Buick?

Costs can range from $50 to $500 depending on whether the issue is a simple wiring repair or if a major component like the control module or motor needs replacement.

8. Can a software update resolve the U172A code on a Buick?

In some cases, a software update for the Left High Beam Control Module can resolve communication issues and clear the code.

9. Is the U172A code covered under warranty?

It depends on your vehicle's warranty terms and coverage. Check with your Buick dealership for details.

10. What tools are needed to troubleshoot the U172A code on a Buick?

A scan tool capable of reading U-codes, a multimeter for checking electrical connections, and possibly a service manual for wiring diagrams are needed.