2021 Audi A4 0CK Gearbox Humming Noise TSB 2074766/2

Audi has released Technical Service Bulletin (TSB) 2074766/2 to address a specific issue affecting the 2021 Audi A4, particularly those equipped with the DL382 front 0CK gearbox. This bulletin, dated July 31, 2024, supersedes an earlier TSB, Group 37 number 24-18, which was also dated July 31, 2024. The current TSB provides a solution for owners experiencing a distinct humming noise from their vehicle's gearbox. This TSB applies to Audi A4 models from 2017-2020 and Audi A6 models from 2017-2018 equipped with the 0CK gearbox.

This TSB is crucial for owners of affected vehicles, as it outlines a clear diagnostic and repair procedure to eliminate the Audi A4 gearbox humming noise.

Important Warnings

Audi specifies that the described repair measure should only be performed if all criteria, such as PR number(s), part number, control unit data, and software version, are met. Failing to meet these conditions means the measure will not resolve the problem, potentially leading to repeat repairs. In such cases, Audi may reject warranty claims and charge back the cost of parts.

For vehicles outside of any warranty, this Technical Service Bulletin is for informational purposes only. All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual and are subject to review or audit by Audi Warranty.

Symptoms

Owners of a 2021 Audi A4 may notice a specific Audi A4 gearbox humming noise under certain driving conditions. The primary symptom described in TSB 2074766/2 is "Humming noises from the gearbox area when pulling away or driving slowly (< 10 mph) with steering wheel turned." This noise is typically heard when the steering wheel is turned, indicating a potential issue within the differential system. An example of this noise can be viewed via a video link provided in the TSB: https://audi-external.kzoplatform.com/player/medium/2799852085208684506.

Technical Background

The root cause of the humming noise in the 0CK gearbox is identified as a stick/slip effect. This occurs when the front axle differential teeth press against each other. The solution involves using a specialized fluid with additives designed to significantly improve the adhesion and sliding characteristics between these differential teeth, thereby eliminating the noise.

Repair Procedure Summary

The repair procedure outlined in TSB 2074766/2 focuses on replacing the Automatic Transmission Fluid (ATF). Technicians are instructed to follow these steps:

1. Drive the vehicle until the gearbox reaches its optimal operating temperature.
2. Drain the existing ATF from the gearbox.
3. Refill the gearbox with new ATF, using part number G 055 549 A2.
4. Adjust the ATF level precisely according to the instructions in the Workshop Manual.
5. Drive the vehicle again until the gearbox reaches operating temperature.
6. Finally, assess the customer's complaint to ensure the humming noise has been resolved.

If the initial conditions for the repair are confirmed, technicians must document their findings with an audio/video file.

Required Parts and Tools

The primary part required for this repair is new Automatic Transmission Fluid (ATF) with part number G 055 549 A2. Technicians must also refer to the Workshop Manual for detailed instructions on ATF level adjustment and other repair specifics. Always check with your Parts Department and/or ETKA for the latest information and parts bulletins, and consult the Repair Manual for any fasteners, bolts, nuts, and screws that require replacement.

Warranty Information

For eligible vehicles, warranty claims related to this issue should be submitted using the following details:

• Service Number: 3912
• Damage Code: 0020
• Labor Operations:
  • Replace gear oil: 3401 5599 (70 Time Units)
  • Diagnostic Time (GFF): 0150 0000 (Labor according to the diagnostic log)
  • Charge battery: 2706 8950 (According to APOS)

Claim comments should reference TSB 2074766/2.

Owner Action

If you own a 2017-2020 Audi A4 or a 2017-2018 Audi A6 with a 0CK gearbox and are experiencing a Audi A4 gearbox humming noise when pulling away or driving slowly with the steering wheel turned, it is recommended to contact your authorized Audi dealership. Provide them with the details of the noise and mention Technical Service Bulletin 2074766/2. The dealership will be able to diagnose the issue and perform the necessary ATF replacement if your vehicle is covered by the TSB.

---

Source: NHTSA ID 10255959