2021-2023 Audi e-tron ABS/ESC Module No Communication TSB

Audi has released Technical Service Bulletin (TSB) 45 24 45 2072977/3 to address a specific communication issue affecting the ABS/ESC control unit in certain e-tron models. This bulletin, dated July 31, 2024, supersedes a previous TSB, 45 24-40, from March 22, 2024, and outlines an updated service procedure.

This TSB is crucial for owners experiencing symptoms related to the braking system and dashboard warnings. The primary concern is the diagnostic trouble code (DTC) "U012100 ABS Control Module no communication," which indicates a problem with the ABS/ESC control unit -J104-.

Symptoms Owners May Notice

Owners of affected Audi e-tron vehicles may experience a noticeable reduction in braking assistance. Additionally, various warning lamps may appear in the instrument cluster, alerting the driver to a potential issue with the vehicle's braking or stability control systems. These symptoms directly relate to the "Audi e-tron U012100" fault.

Fault Codes

The core of this issue is identified by specific diagnostic trouble codes (DTCs) that technicians will find when scanning the vehicle's systems. The primary fault code is:

• U012100 (Symptom Code 19875): "ABS Control Module no communication"

This DTC is typically logged in diagnostic address 0001, indicating that the ABS/ESC control unit -J104- (Diagnostic address 0003) cannot be reached in communication.

Technical Background of the Issue

The problem stems from an unexpected restart of the ABS/ESC control unit -J104-. When this occurs, the electromechanical brake servo remains in a hydraulic fallback level, and bus communication with other vehicle systems ceases. This lack of communication triggers driver messages and warning lamps in the instrument cluster. Audi notes that this restart is a rare event and that the control unit itself is not adversely affected by the restart once a software update is performed.

Important Warning

Audi explicitly states a critical instruction for technicians regarding this issue:

• "Do not replace any component. Any control unit replacement for this concern may be denied."

This warning emphasizes that the solution is a software update, not a hardware replacement, preventing unnecessary repairs and costs.

Repair Procedure Summary

The repair for the "Audi e-tron U012100" issue primarily involves a software update to the ABS/ESC control unit -J104-. The procedure varies slightly depending on the vehicle's current software version.

For Vehicles with ABS/ESC control unit -J104- with software version SW 2XX:

1. The 12V battery must be disconnected from the vehicle for 5 minutes.
2. After reconnection, the accessibility of the control unit -J104- is checked via diagnosis.
3. Technicians must ensure the current software for the ABS unit is at least version 242. If it is below this level, they are instructed to review Field Campaign 93N1 for necessary updates before proceeding.
4. The parking brake is released.
5. A software update is performed following instructions in TSB 2011732: 00 Software Version Management (SVM), operating instructions.
6. The ABS control unit (J104) is updated using SVM action code 03A036.
7. After the update, Basic Settings for the Parking Brake and TPMS are performed.

For Vehicles with ABS/ESC control unit -J104- with software version SW 321:

1. The 12V battery must be disconnected from the vehicle for 5 minutes.
2. The accessibility of the control unit -J104- is checked via diagnosis.
3. The parking brake is released.
4. A software update is performed following instructions in TSB 2011732: 00 Software Version Management (SVM), operating instructions.
5. The ABS control unit (J104) is updated using SVM action code 03A039.
6. After the update, Basic Settings for the Parking Brake and TPMS are performed.

Once these steps are completed and no DTCs are stored in the J104 that would require further repair, the vehicle is ready for use.

Required Parts and Software

The primary resolution is a software update. Technicians will use specific SVM action codes and software part numbers depending on the vehicle's current software level:

• For SW 2XX vehicles: SVM action code 03A036 updates software part numbers like 4KE909059N (from SW 242, 243, or 244) and 4KE909059G (from SW 242 or 243) to software version 245.
• For SW 321 vehicles: SVM action code 03A039 updates software part number 4KE909059AN (from SW 321) to software version 322.

Warranty Information

This Technical Service Bulletin provides information for repairs. If the vehicle is outside of its warranty period, this TSB serves as informational guidance only, and any repairs may not be covered. Warranty claims must adhere to the Audi Warranty Policies and Procedures Manual. The service number for this issue is 4545, with a damage code of 0040. Labor operations include loosening and securing the earth strap (9785 0999), checking vehicle bus sleep mode (0689 0199), and software updates (0151 0010 or 0151 0060).

Revision History

This TSB has undergone several revisions:

• Revision 1 (February 14, 2024): Initial publication.
• Revision 2 (March 22, 2024): Revised service procedure and updated warranty labor operations.
• Revision 3 (July 31, 2024): Further revised service procedure.

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Source: NHTSA ID: 11005891