2021-2023 Audi B101C07 Seat Belt Warning TSB

Symptoms

Owners of affected 2021-2023 Audi vehicles may experience a sporadic "seat belt warning" or "Pre Sense warning" message appearing in the Driver Information System (DIS) while driving. This issue is often accompanied by a diagnostic trouble code (DTC) stored in the airbag control module.

Fault Codes / DTCs

When the "seat belt warning" or "Pre Sense warning" appears, technicians may find the following diagnostic trouble code stored in the airbag control module/safety computer, identified as J234 (address word 0015):

Code	Description
B101C07	Driver seat belt switch mechanical malfunction

Diagnosis and Trigger Conditions

The Safety Computer continuously monitors the status of the seat belt latch switch, E24. If a seat belt extender, a seat belt cheat device, or a continuously buckled seat belt is used, the Safety Computer receives a constant signal that the seat belt is latched. If the Safety Computer does not detect a change in the belt latch switch signal over five consecutive drive cycles, it will store DTC B101C07.

This condition leads to the activation of the "Pre Sense warning" in the DIS, as the system assumes a seat belt cheat device is installed. A complete drive cycle, as defined by Audi, consists of 11 steps:

1. Unlock door.
2. Open door.
3. Close door.
4. Latch seat belt.
5. Turn on ignition and drive.
6. Park.
7. Unlatch seat belt.
8. Turn off ignition.
9. Open door.
10. Close door.
11. Lock door.

Important Warnings for Owners

Owners should be aware of critical information regarding this issue:

• Safety Risk: "The risk of serious or fatal injury increases if the seat belt is not fastened, if it is worn incorrectly, or if it is damaged." Always ensure seat belts are properly fastened for safety. Refer to your owner's manual for additional information and warnings.
• Parts Replacement: "Parts replacement does not solve this issue. Claims for replaced parts will be subject to review." This means that replacing the seat belt latch switch will not resolve the underlying cause of the Audi B101C07 seat belt warning if it's due to an extender or continuous buckling.
• Warranty: This Technical Service Bulletin is informational only and does not apply to any Audi Warranty claims.

Repair Procedure Summary

For vehicles exhibiting the Audi B101C07 seat belt warning, the service procedure involves:

1. Connecting the vehicle to ODIS Service and performing a Guided Fault Finding (GFF) scan.
2. If DTC B101C07 is stored, technicians should follow all applicable GFF test plans.
3. If the GFF indicates that the seat belt latch switch is not defective, the customer should be informed that the use of a seat belt extender, a seat belt cheat device, or continuously buckled seat belts could be the cause of this concern.
4. Performing one drive cycle with the seat belt being latched and unlatched is sufficient to change the DTC B101C07 from static to sporadic and to turn off the "Pre Sense warning" in the instrument cluster.

TSB Revision History

This Technical Service Bulletin has undergone several revisions:

• Revision 5 (November 17, 2021): Revised header, added model years and models, and corrected an Elsa display issue.
• Revision 4 (August 5, 2021): Revised header and added model years.
• Revision 3 (September 1, 2020): Revised header and added model years and models.

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Source: NHTSA ID: 10203595