AutoCodes – Buick – U0421 Buick

U0421 Buick Code - Invalid Data Received From Suspension Control Module

Quick Answer

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Faulty Suspension Control Module 'A', Suspension Control Module 'A' harness is open or shorted, Suspension Control Module 'A' 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: U0421 Buick indicates Invalid Data Received From Suspension Control Module.
Common causes: Common causes include Faulty Suspension Control Module 'A', Suspension Control Module 'A' harness is open or shorted, Suspension Control Module 'A' 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 611

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 12, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0421 Buick Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. Some devices are constantly receiving information from other devices through serial data communication network. The invalid data Diagnostic Trouble Code (DTC) will be set when a receiving device detects a discrepancy in the information it receives from the Suspension Control Module 'A' causing its integrity to be questioned.

OBDII Code U0421 Buick - Invalid Data Received From Suspension Control Module - AutoCodes.com — U0421 Buick Code - Invalid Data Received From Suspension Control Module

What does this mean?

What are the Possible Causes of the DTC U0421 Buick?

Faulty Suspension Control Module 'A'
Suspension Control Module 'A' harness is open or shorted
Suspension Control Module 'A' circuit poor electrical connection

How to Fix the DTC U0421 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 U0421 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 U0421 Buick Code

1. What does the OBDII code U0421 mean on a Buick?

The U0421 code means the vehicle's suspension control module is sending invalid or corrupted data to other modules on the network.

2. What are the common symptoms of code U0421 in a Buick?

Symptoms may include a check engine light, suspension warning lights, noticeable changes in ride height or quality, and potentially reduced vehicle stability.

3. What causes the U0421 code to appear in a Buick?

Common causes include a faulty suspension control module, damaged wiring or connectors, software issues, or communication errors in the vehicle's CAN bus system.

4. Can I drive my Buick with the U0421 code active?

While the vehicle may still be drivable, it could experience compromised suspension performance or handling, which may impact safety. It's best to address the issue promptly.

5. How is the U0421 code diagnosed on a Buick?

A technician will use a scan tool to check for related codes, inspect the suspension control module, check wiring and connectors, and test the CAN bus communication system.

6. How can I fix the U0421 code on my Buick?

Repair options may include updating or reprogramming the suspension control module, repairing damaged wiring, replacing faulty connectors, or replacing the module if necessary.

7. Can the U0421 code be caused by a dead car battery?

Yes, a low or dead battery can sometimes cause communication errors between modules, triggering the U0421 code.

8. Does a faulty suspension sensor trigger the U0421 code on a Buick?

A faulty suspension sensor might not directly trigger U0421, but it can provide bad data to the suspension control module, leading to communication issues.

9. Is the U0421 code related to Buickâ€™s air suspension system?

Yes, if your Buick is equipped with air suspension, the U0421 code may indicate a problem with the air suspension control module or its communication with other systems.

10. Will clearing the U0421 code solve the problem?

Clearing the code may temporarily turn off the warning light, but the issue will likely return unless the underlying problem is fixed.