2021-2022 Audi e-tron Sportback ABS/ESC Control Unit TSB

Important Warnings

Audi explicitly states, "Do not replace any component. Any control unit replacement for this concern may be denied." This means technicians should prioritize the software update outlined in this bulletin rather than replacing hardware. Owners should be aware that unnecessary parts replacement may not be covered under warranty.

Additionally, for "Vehicles equipped with ABS/ESC control unit with software version SW321, please review: PSS 2073483: 45 PSS ABS/ESC control unit cannot be reached "DTC U012100 ABS Control Module no communication" stored and follow instructions." This indicates a specific subset of vehicles may require a different, related procedure.

Symptoms

Owners of affected Audi e-tron models may experience several noticeable issues related to the braking system and vehicle stability. The primary symptom is reduced braking assistance, which can impact vehicle safety. Concurrently, various warning lamps may illuminate in the instrument cluster, alerting the driver to a problem.

During diagnosis, technicians will find that the ABS/ESC Control unit -J104- (Diagnostic address 0003) cannot be reached in communication. This communication failure is also logged as the diagnostic trouble code (DTC) "U012100 (Symptom Code 19875), ABS Control Module no communication" in diagnostic address 0001.

Fault Codes / DTCs

The following diagnostic trouble code is associated with this issue:

Code	Description	Module	Symptom Code
U012100	ABS Control Module no communication	ABS/ESC Control Unit -J104-	19875

Technical Background

The root cause of the "Audi e-tron Sportback ABS control module no communication" issue stems from the control unit -J104- performing an unexpected restart. Following this restart, the electromechanical brake servo remains in a hydraulic fallback mode, and bus communication ceases. This interruption in communication leads to various driver messages being displayed from other vehicle systems. Audi notes that this restart is a rare occurrence.

Repair Procedure Summary

The repair for the "Audi e-tron Sportback ABS control module no communication" involves a specific software update and system reset. The procedure, detailed in Technical Service Bulletin 2072977/2, begins by disconnecting the 12V battery for five minutes to reset the system. After reconnecting, technicians must verify that the ABS/ESC control unit -J104- is accessible for diagnosis.

A critical step is to ensure the current software version for the ABS control unit -J104- is at least 242. If the software level is below 242, technicians are instructed to check for and apply updates from Field Campaign 93N1 before proceeding. The parking brake must then be released.

The core of the repair is performing a software update on the ABS control unit -J104-. This is done using the Software Version Management (SVM) system, following instructions from TSB 2011732. The SVM action code required for this update is 03A036. For models like the e-tron/Q8 e-tron, old software part numbers 4KE909059N (versions 242, 243, 244) and 4KE909059G (versions 242, 243) are updated to version 245 of their respective part numbers.

After the software update, a basic settings adaptation must be performed for both the Parking Brake and the Tire Pressure Monitoring System (TPMS). Finally, if no DTCs are stored in the ABS control unit -J104-, the vehicle can be released. If DTCs persist, further diagnosis following Guided Fault Finding (GFF) instructions is necessary.

Required Tools or Parts

This repair primarily involves software updates rather than physical part replacement. Technicians will need access to the Audi diagnostic system for Software Version Management (SVM) and the specific SVM action code 03A036. The software update targets existing ABS control unit part numbers 4KE909059N and 4KE909059G, updating them to version 245.

Warranty Information

This Technical Service Bulletin (TSB) 2072977/2 outlines specific warranty claim procedures. For vehicles under the new vehicle limited warranty (up to 48 months/50,000 miles), the repair is covered. Certified Pre-Owned (CPO) vehicles also qualify under claim type G10, provided ownership is verified. If the vehicle is outside of any warranty, this TSB serves as informational guidance only.

The service number for this bulletin is 4545, with a damage code of 0040. Labor operations include specific time units (TU) for tasks such as loosening and securing the earth strap (10 TU), checking the vehicle in bus sleep mode (10 TU), and software updates including DTC checks (up to 50 TU). Road tests before and after the service procedure are listed with no allowance. All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual.

NHTSA ID: 10252097