2021-2022 Audi e-tron Parking Brake Warning TSB

Owners of 2021-2022 Audi e-tron vehicles may experience an intermittent "Parking brake fault" warning appearing in the instrument cluster when starting the vehicle. This condition is often accompanied by the storage of Diagnostic Trouble Code (DTC) U103100 in the Anti-lock Brake System (ABS) control module.

Symptoms

The primary symptom of this issue is a brief illumination of the electronic parking brake warning lamp, along with the specific message, "Parking brake fault," displayed in the instrument cluster upon vehicle startup. This indicates a potential communication problem within the vehicle's FlexRay data bus.

Fault Codes / DTCs

When diagnosing this issue, technicians may find the following DTC stored sporadically in the ABS control module, identified as J104 (address word 0003):

Code	Description
U103100	FlexRay data bus, no synchronization

This DTC points to an underlying communication error that triggers the Audi e-tron parking brake warning.

Diagnosis / Trigger Conditions

Workshop findings confirm that the DTC U103100 is stored sporadically in the ABS control module, J104. This indicates a software-related communication glitch rather than a consistent hardware failure. The Audi e-tron parking brake warning typically appears during the vehicle's startup sequence.

Repair Procedure Summary

The resolution for the Audi e-tron parking brake warning involves updating the software in the affected control modules. The procedure is as follows:

1. Prepare for Update: Follow all instructions detailed in Technical Service Bulletin (TSB) 2011732, titled "00 Software Version Management (SVM), operating instructions."
2. Software Update: Update the ABS control module (J104, address word 0003) and the suspension control module (J775, address word 0074). This is performed using the SVM action code 74A006.
   • For the ABS control module, the software is updated from an older part number like 4KE909059AD (version 0231) to the new part number 4KE909059AF (version 0242 or higher).
   • For the suspension control module, the software is updated from an older part number like 4KE907777AM (version less than 2320) to the new part number 4KE907777AH (version 2320 or higher).
3. Basic Settings: After the software update, perform basic settings for both the electromechanical parking brake and the tire pressure monitoring system.

Required Tools or Parts

To complete this repair, technicians will need access to the Audi diagnostic system for software updates. The specific software versions and part numbers required are:

• ABS Control Module: New Software Part Number 4KE909059AF (version 0242 or higher)
• Suspension Control Module: New Software Part Number 4KE907777AH (version 2320 or higher)
• SVM Action Code: 74A006

Additionally, reference TSB 2011732, "00 Software Version Management (SVM), operating instructions," is necessary for proper execution of the software update.

Important Warnings

Note: If the DTC U103100 remains in the ABS control module, J104 (address word 0003), even after the software update, additional steps are required:

1. Lock the vehicle.
2. Wait until the sleep bus mode is activated.
3. Read the ABS memory log and delete any remaining DTCs in the ABS control module, J104 (address word 0003).
4. Reevaluate the vehicle to ensure the Audi e-tron parking brake warning is resolved.

Owner Action

If your 2021-2022 Audi e-tron is displaying the "Parking brake fault" message or you suspect it may be affected by DTC U103100, it is recommended to visit an authorized Audi dealership. They can diagnose the issue and perform the necessary software update.

This repair is typically covered under warranty for vehicles up to 48 months or 50,000 miles, under Claim Type 110. For Audi Certified Pre-Owned (CPO) vehicles, Claim Type G10 applies. If your vehicle is outside of warranty, this Technical Service Bulletin serves as informational guidance.

NHTSA ID: 10198482