2022-2025 Audi Q8 Electrical System Fault TSB 2072008/2

Audi has issued Technical Service Bulletin (TSB) 2072008/2 to address a common concern in various 2022-2025 Audi models equipped with a 48V battery system. This TSB provides critical information for diagnosing and resolving the "Electrical system: fault" message that may appear in the instrument cluster, often linked to diagnostic trouble code (DTC) B200094.

This bulletin, dated September 10, 2024, supersedes a previous bulletin, Group 91 number 23-47, from November 15, 2023. It aims to guide technicians and owners through the correct diagnostic path for this specific Audi Q8 electrical system fault and similar issues across affected models.

Symptoms

Owners of affected Audi vehicles may observe several indicators of an Audi Q8 electrical system fault:

• A message displayed in the instrument cluster stating: "Electrical system: fault. See owner's manual".
• Another specific warning message: "Electrical system: malfunction! Please contact Service".
• The battery symbol illuminating in yellow or red on the dashboard.
• A yellow warning lamp related to the electrical system appearing in the instrument cluster while driving.

Fault Codes / DTCs

When these symptoms occur, a diagnostic scan will typically reveal the following diagnostic trouble code:

Code	Description	Module
B200094	Faulty control module, passive/active	Voltage converter (00C4)

This DTC indicates a functional problem within the vehicle's voltage converter, which is a key component of the 48V electrical system.

Important Warnings

Audi has issued specific warnings regarding the diagnosis and repair of this Audi Q8 electrical system fault:

• Do not replace the belt-driven starter-alternator C29: The TSB explicitly states: "If the above entry is logged, replacing the belt-driven starter-alternator C29 will not fix the complaint. The failure will occur again if the belt-driven starter-alternator is replaced."
• Claims for review: "Claims for replaced belt-driven starter-alternators will be subject to review." This highlights the importance of correct diagnosis to avoid unnecessary part replacements and potential warranty claim rejections.

Diagnosis and Repair Summary

The root cause of the B200094 DTC and the "Electrical system: fault" message is a functional issue within the voltage converter. To properly address this, technicians must determine the exact cause of the DTC using Guided Fault Finding (GFF).

The repair procedure involves following the Guided Fault Finding protocol, which will lead to the specific steps required to resolve the voltage converter issue. This ensures that the correct component or system is addressed, rather than incorrectly replacing the starter-alternator.

Warranty Information

For vehicles still under warranty, claims for this repair should be submitted according to the Audi Warranty Policies and Procedures Manual. The TSB outlines specific labor operations for Guided Fault Finding:

• Labor Operation 0150 0010: GFF / Guided Functions, with associated operations as per the Service Repair Time (SRT).
• Labor Operation 0150 0060: GFF / Guided Functions, covering the time stated on the diagnostic protocol.

All claims are subject to review or audit by Audi Warranty. If the vehicle is outside of its warranty period, this Technical Service Bulletin serves as informational guidance for diagnosis and repair.

NHTSA ID: 11009386