AutoCodes – GMC – U0421 GMC

U0421 GMC 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 GMC 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 1,908

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

What does this mean?

What are the Possible Causes of the DTC U0421 GMC?

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 GMC?

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 GMC 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 GMC Code

1. What are the common symptoms of OBDII code U0421 in a GMC vehicle?

- Common symptoms include issues with the vehicle's suspension system, such as erratic behavior, harsh ride quality, or suspension warning lights on the dashboard.

2. What does the OBDII code U0421 "Invalid Data Received From Suspension Control Module" mean in a GMC?

- This code indicates that the engine control module (ECM) has detected a communication problem with the suspension control module, leading to invalid or missing data.

3. What are the possible causes of OBDII code U0421 in a GMC related to the suspension control module?

- Potential causes include damaged wiring or connectors, a faulty suspension control module, software issues, or a malfunctioning ECM.

4. How can I diagnose the OBDII code U0421 in my GMC to pinpoint the issue?

- Diagnosing this code typically involves checking the wiring and connectors for damage, verifying the connections to the suspension control module, and performing a scan for any related trouble codes.

5. What are some repair tips for resolving OBDII code U0421 in a GMC?

- Repair tips may include inspecting and repairing any damaged wiring, ensuring proper connections to the suspension control module, updating software if needed, or replacing a faulty suspension control module.

6. Can driving with the OBDII code U0421 in a GMC cause further damage to the vehicle?

- Continuing to drive with this code may lead to further suspension system issues or potential safety concerns due to unreliable suspension control data.

7. Is it safe to temporarily ignore the OBDII code U0421 in a GMC?

- While you may not experience immediate drivability issues, it's recommended to address this code promptly to prevent any potential suspension system malfunctions or safety risks.

8. How much does it typically cost to repair OBDII code U0421 in a GMC at a dealership or repair shop?

- Repair costs can vary depending on the exact cause of the code, but expect expenses for diagnostics, parts replacement, and labor, potentially ranging from a hundred to a few hundred dollars.

9. Can I reset the OBDII code U0421 in my GMC using an OBDII scanner, or does it require professional intervention?

- You can attempt to clear the code using an OBDII scanner, but if the underlying issue is not resolved, the code may reappear. Professional intervention may be necessary for a thorough diagnosis and repair.

10. Are there any recalls or technical service bulletins related to OBDII code U0421 in GMC vehicles?

- It's advisable to check with GMC dealerships or online databases to see if there are any recalls or technical service bulletins addressing this specific OBDII code and related issues in GMC vehicles.