2025 Audi A3 / S3 'Vehicle electronics: fault' TSB

Owners of 2025 Audi A3 and S3 models may encounter an intermittent warning message in their instrument cluster: "Vehicle electronics: fault. Shift to P before leaving vehicle. Please contact workshop". This message, along with diagnostic trouble codes (DTCs) U112300 and B101C07, is addressed by Audi Technical Service Bulletin 34 24 74 2076134/2, which supersedes the previous bulletin 34 24-73 dated November 26, 2024.

This TSB clarifies that this specific message typically does not indicate a functional issue with the vehicle. Instead, it relates to the vehicle's roll-away prevention system, which monitors driver presence through the seat belt buckle status. If you are seeing the "Audi S3 vehicle electronics fault" message, understanding the system's behavior can help.

Symptoms

The primary symptom is the intermittent appearance of the message "Vehicle electronics: fault. Shift to P before leaving vehicle. Please contact workshop" in the instrument cluster. Importantly, the TSB notes that there are no other yellow or red instrument cluster messages, and no functional issues are found on the vehicle when this message appears.

Fault Codes / DTCs

When the "Audi S3 vehicle electronics fault" message is triggered, the following diagnostic trouble codes (DTCs) may be logged:

• U112300 Data bus error value received (symptom 8667429): This code is logged in the diagnostic address 0009 (onboard supply control unit) under two conditions:
  • When the seat belt is permanently fastened for 5 consecutive driving cycles.
  • When the seat belt is permanently unfastened for 5 consecutive driving cycles.
• B101C07 Driver seat belt switch mechanical malfunction: This code is logged in the diagnostic address 0015 (airbag control unit) specifically when the seat belt is permanently fastened for 5 consecutive driving cycles. It is not logged if the belt is permanently unfastened.

Diagnosis and Trigger Conditions

The message and associated DTCs are triggered by the vehicle's internal logic for roll-away prevention. This system monitors the seat belt buckle status across multiple driving cycles. A driving cycle is defined by a sequence of events: unlocking, door opened/closed, ignition on, driving above 10 km/h, ignition off, door opened/closed, and locking.

The system flags an implausible condition if the seat belt buckle status (fastened or unfastened) does not change for five consecutive driving cycles. This can happen if the seat belt is permanently fastened (e.g., using a dummy clip) or permanently unfastened (e.g., during maneuvering where the driver does not buckle up). The vehicle detects this lack of change as an inconsistency in the belt recognition status.

Technicians can monitor the