AutoCodes – Generic – U121A

U121A Code - Hard Disk Drive Write Malfunction

Quick Answer

Integrates Hard Disk Drive (HDD) allowing map data and music data to be stored. Common causes include Faulty Audio and Video (AV) Control Unit, Audio and Video Control Unit harness is open or shorted, Audio and Video Control Unit 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: U121A indicates Hard Disk Drive Write Malfunction.
Common causes: Common causes include Faulty Audio and Video (AV) Control Unit, Audio and Video Control Unit harness is open or shorted, Audio and Video Control Unit 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 2,098

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 May 04, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code U121A Description

Integrates Hard Disk Drive (HDD) allowing map data and music data to be stored. It is the master unit of the MULTI AV system, and it is connected to each control unit by means of communication. It operates each system according to communication signals from the AV control unit. The AV control unit includes the audio, hands-free phone, voice control, navigation, and vehicle information functions. It is connected to ECM and combination meter via CAN communication to obtain necessary information for the vehicle information function.
The Diagnostic Trouble Code (DTC) sets when the Audio and Video (AV) Control Unit detects an internal malfunction of the Audio and Video (AV) Control Unit (HDD write malfunction).

OBDII Code U121A - Hard Disk Drive Write Malfunction - AutoCodes.com — U121A Code - Hard Disk Drive Write Malfunction

What does this mean?

What are the Possible Causes of the DTC U121A?

Faulty Audio and Video (AV) Control Unit
Audio and Video Control Unit harness is open or shorted
Audio and Video Control Unit circuit poor electrical connection

How to Fix the DTC U121A?

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 U121A 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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Information for Specific Makes

U121A Infiniti — Hard Disk Drive Write Malfunction
U121A Nissan — Hard Disk Drive Write Malfunction

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.