2022-2025 Audi A3/S3/RS 3 Airbag DTC B100B1B / B100A1B

Symptoms

Owners of 2022-2025 Audi A3, S3, and RS 3 vehicles may notice the airbag indicator lamp illuminating on the dashboard. This visual warning indicates a potential issue with the vehicle's airbag system, which should be addressed promptly.

Fault Codes / DTCs

When the airbag warning lamp illuminates, a diagnostic scan of the airbag control unit (diagnostic address 0015) will typically reveal one of the following event memory entries:

• B100B1B: Driver thorax airbag igniter Resistance too high.
• B100A1B: Front passenger side airbag igniter Resistance too high.

These codes specifically point to an electrical resistance issue within the side airbag igniter circuit.

Diagnosis / Trigger Conditions

The root cause of the high resistance is identified as the side airbag wiring being positioned too close to the seat foam. Over time, the seat foam can press on the wire, causing the connector to move and leading to an increase in electrical resistance within the circuit. This condition triggers the airbag warning light and logs the specific DTCs, such as the Audi S3 airbag DTC B100B1B.

To determine the appropriate repair, technicians will check the frequency counter in the event memory. This counter helps assess the severity and persistence of the fault.

Repair Procedure Summary

The repair procedure outlined in TSB 69 24 15 2075121/1 varies depending on the frequency counter value:

• If the frequency counter in the event memory is less than 20: The technician will unplug and then re-plug the side airbag connector to ensure proper contact of all four pins. The wiring harness will then be re-routed according to specific instructions and secured using clips, such as N10546701 or 4N0971850A, to prevent future contact with the seat foam.

• If the frequency counter in the event memory is 20 or greater: The wiring harness for the side airbag must be replaced. After replacement, the new wiring harness is attached to the seat frame using clips N10546701 or 4N0971850A, following the specified routing to ensure it remains clear of the seat foam.

After either repair, it is critical to ensure the connector is securely locked.

Required Tools or Parts

For this repair, specific clips are required to properly secure the wiring harness:

• Clip N10546701
• Clip 4N0971850A

In cases where the frequency counter is 20 or greater, a new side airbag wiring harness will also be required.

Important Warnings

IMPORTANT: Lock connector again afterwards! This step is crucial to ensure the integrity and safety of the airbag system connection.

Owners should also be aware that if the vehicle is outside of its warranty period, this Technical Service Bulletin is informational only, meaning the repair may not be covered under warranty. All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual.

Owner Action

If your 2022-2025 Audi A3, S3, or RS 3 displays an airbag warning light or you suspect an issue related to the Audi S3 airbag DTC B100B1B or B100A1B, it is recommended to schedule an appointment with an authorized Audi service center. Provide them with the details of the warning light and any diagnostic codes you may have observed. The service center will perform the necessary diagnosis and apply the appropriate repair procedure as outlined in TSB 69 24 15 2075121/1.

NHTSA ID: 11009374