AutoCodes – Buick – U2120 Buick

U2120 Buick Code - Lost Communication With Dynamic Headlamp Leveling Device

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Dynamic Headlamp Leveling (DHL) Device, Dynamic Headlamp Leveling Device harness is open or shorted, Dynamic Headlamp Leveling Device 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: U2120 Buick indicates Lost Communication With Dynamic Headlamp Leveling Device.
Common causes: Common causes include Faulty Dynamic Headlamp Leveling (DHL) Device, Dynamic Headlamp Leveling Device harness is open or shorted, Dynamic Headlamp Leveling Device 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 520

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 16, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U2120 Buick Description

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver device as an availability indication of the transmitter device. Each message contains the identification number of the transmitter device. A loss of serial data communications Diagnostic Trouble Code (DTC) does not represent a failure of the devices that contain the stored code. The DTC will set when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U2120 Buick - Lost Communication With Dynamic Headlamp Leveling Device - AutoCodes.com — U2120 Buick Code - Lost Communication With Dynamic Headlamp Leveling Device

What does this mean?

What are the Possible Causes of the DTC U2120 Buick?

Faulty Dynamic Headlamp Leveling (DHL) Device
Dynamic Headlamp Leveling Device harness is open or shorted
Dynamic Headlamp Leveling Device circuit poor electrical connection

How to Fix the DTC U2120 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 U2120 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 U2120 Buick Code

1. What are common symptoms of OBDII code U2120 in a Buick related to the dynamic headlamp leveling device?

- Common symptoms include malfunctioning automatic headlight leveling, flickering or misaligned headlights, and dashboard warning lights.

2. What are possible causes of the U2120 code indicating lost communication with the dynamic headlamp leveling device in a Buick?

- Possible causes may include a faulty headlamp leveling control module, damaged wiring or connectors, or a communication network issue within the vehicle.

3. How can I diagnose the U2120 code in my Buick related to the dynamic headlamp leveling device?

- Diagnose the issue by checking the wiring and connectors for damage, inspecting the headlamp leveling control module, and using a diagnostic scan tool to communicate with the system.

4. What are some repair tips for fixing the U2120 code indicating lost communication with the dynamic headlamp leveling device in a Buick?

- Repair tips may involve repairing or replacing damaged wiring, connectors, or components, resetting the system, and ensuring proper communication between modules.

5. Can the U2120 code in a Buick related to the dynamic headlamp leveling device cause safety concerns?

- Yes, as the dynamic headlamp leveling system contributes to optimal visibility while driving at night, addressing this issue promptly is important for safety on the road.

6. Is it possible to reset the U2120 code in a Buick without addressing the underlying issue?

- While clearing the code may temporarily turn off the warning light, it is crucial to diagnose and repair the root cause to prevent the problem from reoccurring.

7. Are there any recalls or technical service bulletins related to the U2120 code in Buick vehicles?

- It is recommended to check with the manufacturer or authorized dealerships for any recalls or technical service bulletins specific to the U2120 code in Buick models.

8. Can a DIY enthusiast with basic automotive knowledge fix the U2120 code in a Buick at home?

- Depending on the root cause, DIY repairs may be possible for those with the necessary tools and expertise, such as checking and repairing wiring connections.

9. Will ignoring the U2120 code related to the dynamic headlamp leveling device in a Buick lead to further vehicle damage?

- Ignoring the code may result in potential headlight malfunction, reduced visibility at night, or other related issues, impacting overall driving safety.

10. How can regular maintenance help prevent the occurrence of the U2120 code in a Buick?

- Regular maintenance, including inspecting and maintaining the headlamp leveling system, can help prevent issues that may trigger the U2120 code in Buick vehicles.