2019-2026 Audi Q7 Q8 Starter Generator Fault TSB

Audi has released Technical Service Bulletin (TSB) 2076994/5, scheduled for publishing on October 24, 2025, to address concerns related to the Valeo 48V starter generator (BSG) system in several models, including the 2019-2026 Audi Q7 and Q8. This TSB specifically targets a range of Diagnostic Trouble Codes (DTCs) that can indicate malfunctions within the 48V electrical system and the starter generator control module.

The 48V mild-hybrid system, which includes the starter generator, plays a crucial role in modern Audi vehicles, supporting functions like engine start/stop, coasting, and energy recuperation. When this system encounters issues, it can trigger an engine warning lamp and log specific fault codes, prompting the need for diagnosis and repair.

Revision History

This Technical Service Bulletin (TSB) 2076994/5 has undergone several revisions, indicating ongoing updates to address the 48V starter generator issue:

• Revision 5: Updated header (including MY26 and software versions), revised condition (added customer concerns and workshop findings), revised service (updated verbiage and ETA for future software arrival), and updated warranty table.
• Revision 4 (July 31, 2025): Revised service section, specifically updating the fault table.
• Revision 3 (May 7, 2025): Revised header (including fault codes, customer codes, and workshop codes), revised condition (added customer concerns), revised service (added fault table), and revised warranty (added replacement part note).

Symptoms Owners May Notice

Owners of affected Audi vehicles, such as the 2019-2026 Audi Q7 and Q8, may primarily notice the illumination of the "engine warning lamp (MIL) is on" on their instrument cluster. This warning light, depicted in Figure 1 of the TSB as a yellow engine symbol, indicates a detected fault within the engine or emissions system, but in this context, it points to an issue with the 48V starter generator.

While the TSB does not explicitly list other direct owner-perceptible symptoms, underlying electrical system malfunctions can sometimes manifest as inconsistent engine start/stop operation or general electrical anomalies. Dealerships have reported various customer complaints related to the electrical system, including general inspection and maintenance requests, vehicle electrical system malfunction indicators, and issues with power supply and data transfer, all potentially linked to the starter generator or its control module.

Fault Codes / DTCs

When the engine warning lamp illuminates due to an Audi Q7 Q8 starter generator fault, specific Diagnostic Trouble Codes (DTCs) will be stored in the vehicle's control modules. These codes help technicians pinpoint the exact nature of the problem. TSB 2076994/5 lists numerous DTCs, primarily associated with the '00CC - Starter generator' diagnostic address (control unit C29) and, in some cases, '0001 - Engine electronics' (control unit J623).

Here is a comprehensive list of DTCs covered by this TSB:

Diagnostic Address	Diagnostic Trouble Code	Fault Symptom	Storage State
00CC - Starter generator	P2DC500	Starter/Generator Phase Z Current Sensor Circuit	static
00CC - Starter generator	P0E0400	Generator Phase V Current Sensor Circuit	static
00CC - Starter generator	P0E0600	Generator Phase V Current Sensor Circuit Low	intermittent
00CC - Starter generator	P19F800	48-volt vehicle electrical system not available	static
00CC - Starter generator	P0E0000	Generator Phase U Current Sensor Circuit	intermittent
00CC - Starter generator	P0A1A00	Generator Control Module	intermittent
00CC - Starter generator	U014600	Lost Communication With Serial Data Gateway Module "A"	intermittent
00CC - Starter generator	U300100	Control Module Improper Shutdown Performance	intermittent
00CC - Starter generator	P056100	System Voltage Unstable	intermittent
00CC - Starter generator	P2DC300	Starter/Generator Phase Y Current Sensor Circuit	static
00CC - Starter generator	P0E0200	Generator Phase U Current Sensor Circuit Low	static
00CC - Starter generator	P069800	Sensor Reference Voltage "C" Circuit Low	intermittent
00CC - Starter generator	P19F800	48-volt vehicle electrical system not available	intermittent
00CC - Starter generator	P10F300	Starter generator Release status implausible	intermittent
00CC - Starter generator	P056200	System Voltage Low Voltage	intermittent
00CC - Starter generator	P2DC100	Starter/Generator Phase X Current Sensor Circuit	intermittent
00CC - Starter generator	P0A1E00	Starter/Generator Control Module	intermittent
0001 - Engine electronics	U046900	Invalid Data Received From Starter / Generator Control Module	static
00CC - Starter generator	P2DC500	Starter/Generator Phase Z Current Sensor Circuit	intermittent
00CC - Starter generator	P0E0800	Generator Phase W Current Sensor Circuit	static
00CC - Starter generator	P065200	Sensor Reference Voltage "B" Circuit Low	intermittent
00CC - Starter generator	P0E0000	Generator Phase U Current Sensor Circuit	static
00CC - Starter generator	P0E0200	Generator Phase U Current Sensor Circuit Low	intermittent
00CC - Starter generator	P2DC300	Starter/Generator Phase Y Current Sensor Circuit	intermittent
00CC - Starter generator	P0A1E00	Starter/Generator Control Module	static
00CC - Starter generator	P0E0800	Generator Phase W Current Sensor Circuit	intermittent
00CC - Starter generator	P0E0600	Generator Phase V Current Sensor Circuit Low	static
00CC - Starter generator	P2DC100	Starter/Generator Phase X Current Sensor Circuit	static

Understanding the 'Storage State' is important: 'static' DTCs indicate a persistent fault that is currently present, while 'intermittent' DTCs suggest a fault that occurred but is not necessarily active at the moment of diagnosis. Both types require attention, as intermittent faults can become static or indicate a developing problem within the Audi Q7 Q8 starter generator fault system.

Diagnosis and Trigger Conditions

Diagnosis for the Audi Q7 Q8 starter generator fault typically begins when a customer reports an illuminated engine warning lamp or during a routine workshop visit. Technicians will connect to the vehicle's diagnostic system to read the stored DTCs. The presence of any of the listed DTCs, particularly those related to the '00CC - Starter generator' control module (C29) or '0001 - Engine electronics' (J623), confirms the applicability of TSB 2076994/5.

Workshop findings indicate that these DTCs are stored in their respective modules during service inspections or even while the customer is driving. For example, DTC U046900 in the Engine Electronics module points to an "Alternator control module, implausible signal," which is part of the broader 48V system. The TSB outlines two primary cases for diagnosis and repair based on the specific combination of DTCs present.

Understanding the 48V Mild Hybrid System

The 48V mild hybrid system is a key technology in many modern Audi vehicles, including the 2019-2026 Audi Q7 and Q8. At its heart is the Valeo 48V starter generator (BSG), which replaces the conventional starter motor and alternator. This component performs multiple functions:

• Rapid Engine Starts: Enables quicker and smoother engine restarts for the start/stop system, improving fuel efficiency and reducing emissions.
• Energy Recuperation: Recovers kinetic energy during braking and deceleration, converting it into electrical energy to charge the 48V lithium-ion battery.
• Boost Function: Provides a temporary power boost to the engine during acceleration, enhancing performance.
• Coasting: Allows the engine to switch off while coasting at certain speeds, further saving fuel.

Malfunctions in the starter generator or its control module can disrupt these functions, leading to the various DTCs outlined in TSB 2076994/5. The system relies on precise communication and voltage regulation, and any deviation can trigger faults like "48-volt vehicle electrical system not available" (P19F800) or "Generator Control Module" (P0A1A00).

Production Solution

Audi has implemented new software for the 48V starter generator in production vehicles starting in production week 07/2025. This indicates that vehicles manufactured after this date should already have the updated software that addresses these issues.

Repair Procedure Summary

Audi TSB 2076994/5 outlines a clear repair strategy, primarily focusing on software updates for the Starter Generator, C29 (address word 00CC). The TSB details two main scenarios:

Case 1: Software Update Only

If the Starter Generator, C29, contains any of the listed DTCs except for those related to P0E000 or P2DC (e.g., P2DC500, P0E0400, P0E0600, P0E0000, P2DC300, P0E0200, P2DC100, P0E0800), the repair involves updating the software for the Starter Generator control module. This update is performed using the SVM (Software Version Management) system with code CCA005. The old software version 0606 is updated to 0608 (or higher) using software part number 4M0.903.028*. The TSB explicitly states, "There is no reason to replace parts as this could lead to repeat concerns" in this scenario, emphasizing that the issue is software-related. Technicians must follow all instructions in TSB 2011732: 00 Software Version Management (SVM), operating instructions.

Case 2: Software Update and Potential Hardware Replacement

If the Starter Generator, C29, contains DTC P19F800 AND any P0E000 or P2DC DTCs, this indicates a potential hardware issue in addition to software. In this case, the software for the Starter Generator, C29, must still be updated as described in Case 1. However, the TSB notes that the Starter Generator, C29, may also need to be replaced. This decision is based on further diagnosis and the specific combination of fault codes, suggesting a more complex problem with the Audi Q7 Q8 starter generator fault.

For certain DTCs, specifically P0A1E00, P0A1A00, P069800, P056200, and P065200, the TSB advises to "Postpone repair." For these codes, a new software solution (version 0610) for the 48V BSG is planned for release in week 10/2026. This means that for vehicles exhibiting these specific codes, a permanent fix is not yet available, and owners may need to wait for a future update.

Required Tools or Parts

The primary repair involves a software update using the SVM system. The software part number is 4M0.903.028*, updating from old software version 0606 to new software version 0608 (or higher). The SVM Code Input required for this update is CCA005. In cases where hardware replacement is necessary, the starter generator itself (part number 4M0.903.028*) may be replaced.

Important Warnings and Owner Information

Audi has provided several critical warnings and pieces of information for both technicians and vehicle owners regarding this TSB 2076994/5:

• Do Not Replace Parts Unnecessarily: For Case 1 scenarios (software-only fix), the TSB explicitly states, "There is no reason to replace parts as this could lead to repeat concerns." This prevents unnecessary part replacements and associated costs.
• Warranty Limitations: "Unjustified work/replacement parts will be charged back. Invoicing under warranty is not permitted." Owners should ensure their vehicle is diagnosed correctly under warranty terms.
• Informational Only for Out-of-Warranty Vehicles: "If the vehicle is outside of any warranty, this Technical Service Bulletin is informational only." This means that for vehicles no longer under warranty, the repair costs will not be covered by Audi.
• Software Modifications and Warranty: If the customer or third parties have modified the vehicle's software (e.g., chip tuning or retrofitting), they must be informed that "this software update may neutralize previous modifications to the vehicle's software performed either by the customer or other third parties." Furthermore, customers should be referred to the Warranty and Maintenance booklet to understand how such modifications can impact warranty coverage.
• Declining Software Update: "If the customer declines the software update, please inform them that this could lead to issues or restrictions with the use of the vehicle or individual components." This highlights the importance of the update for vehicle functionality and safety.

Warranty Claim Information

For authorized Audi dealerships, the warranty claim details for TSB 2076994/5 are as follows:

• Service Number: 2726
• Damage Code:
  • Case 1: 0039 (Software Update Only)
  • Case 2: 0040 (Software Update and Potential Hardware Replacement)
• Labor Operations:
  • Software Update - Only if 48V starter/generator is NOT replaced: 0151 0010 (See SRT with associated operations) or 0151 0060 (Time stated on the diagnostic protocol).
  • Remove and install 48V starter/generator - Only if 48V starter/generator IS replaced: 2726 1944 (See SRT with associated operations).
• Claim Comment: As per TSB 2076994/5.

All warranty claims must be submitted in accordance with the Audi Warranty Policies and Procedures Manual and are subject to review by Audi Warranty.

Owner Action

If you own a 2019-2026 Audi Q7 or Q8 and are experiencing an illuminated "engine warning lamp (MIL) is on" or suspect an Audi Q7 Q8 starter generator fault, it is recommended to schedule an appointment with an authorized Audi service center. The technicians will diagnose the vehicle by checking for the specific DTCs outlined in TSB 2076994/5. Depending on the fault codes found, your vehicle may require a software update or, in some cases, a hardware replacement for the 48V starter generator. Be aware that for certain DTCs, a permanent fix is planned for week 10/2026, and repairs may be postponed until then.

NHTSA ID: 10255562