2025-2026 Audi P064F00 MIL On and Engine Start Issues

Audi has issued Technical Service Bulletin (TSB) 2078914/2 to address a specific issue affecting certain 2025-2026 Audi models. This bulletin details a condition where the Malfunction Indicator Lamp (MIL) illuminates, and the engine may fail to start. The root cause is identified as Diagnostic Trouble Code (DTC) P064F00, indicating "Unauthorized Software/Calibration Detected" within the Engine Control Module (ECM).

This TSB, released on October 15, 2025, with revision 2, provides crucial information for technicians and owners regarding the diagnosis and resolution of this fault. If you are experiencing an Audi P064F00 MIL on or related starting problems, this information is highly relevant.

Symptoms Owners May Experience

Owners of affected Audi vehicles may observe the following symptoms:

• "Engine does not start"
• "MIL/ Exhaust emission warning lamp is on."

These symptoms are directly linked to the presence of DTC P064F00 in the ECM.

Fault Codes (DTCs)

The primary diagnostic trouble code associated with this issue is:

Code	Description	Error Type	Status
P064F00	Unauthorized Software/Calibration Detected	active	active/static

This code is stored in the Engine Control Module (ECM), specifically identified as J623 (address word 0001).

Diagnosis and Trigger Conditions

The TSB notes that this issue primarily "only occurs when performing diagnostic work in the workshop." This suggests that the condition might be triggered or become apparent during specific diagnostic procedures involving the vehicle's electronic systems.

Technical Background

According to Audi, the underlying cause of DTC P064F00 is the potential loss of coding for the engine control unit during routine ODIS (Offboard Diagnostic Information System) diagnosis performed in the workshop. The precise reason for this coding loss is currently under analysis by Audi.

Understanding the Engine Control Module (ECM) and P064F00

The Engine Control Module (ECM), also known by its system abbreviation J623, is the central computer responsible for managing the engine's performance. It controls critical functions like fuel injection, ignition timing, and emissions. The ECM relies on specific software and calibration data to operate correctly. When DTC P064F00, "Unauthorized Software/Calibration Detected," is stored, it indicates that the ECM's programming or calibration data has been altered or corrupted in a way that the system no longer recognizes as legitimate or correct. This can lead to the engine failing to start or the MIL illuminating, signaling a critical system fault.

The "Virtual Replacement" Repair Procedure

The repair for this condition involves a process described as a "virtual replacement" of the engine control unit. It is crucial to understand that this does not mean physically replacing the ECM hardware. Instead, it refers to a software-based procedure to restore the correct coding and calibration to the existing ECM.

The service procedure outlined in TSB 2078914/2 requires technicians to:

1. Access diagnostic address 0001, which corresponds to the engine control unit.
2. Perform a procedure to "Replace engine control unit and code it." This action, despite its wording, is a software adaptation and coding process.
3. After the virtual replacement and coding, a functional check must be performed.
4. Finally, the DTC P064F00 must be deleted from the ECM's memory.

This approach ensures that the ECM receives the correct, authorized software and calibration without the need for costly and unnecessary hardware replacement.

Affected Vehicle Details and Technical Identifiers

This TSB applies to specific 2025-2026 Audi models, including the A5, S5, SQ5, and A6. The document provides several technical identifiers related to the ECM and its software, which are critical for technicians during diagnosis and repair:

• Hardware Part Number: 06M907309N, 8B3907559B
• Hardware Version Number: H80
• Software Version Number: 0006
• Production Date: January 16, 2025
• System Name: V6 3.0l TFSI
• ASAM Base Version: BV_EnginContrModul1UDS
• ASAM 2D/ODX Data Set: EV_ECM30TFS0118839075598
• ASAM 2D/ODX Data Set Version: 001007
• Target Data Container: 06M909102BK
• Version of the Target Data Container: 10005
• Engine Codes: DMW*, DXB*

These specific codes and versions help identify the exact software and hardware configuration of the ECM that may be affected by the coding loss, ensuring the correct repair is applied to resolve the Audi P064F00 MIL on issue.

Warranty Information

For vehicles still under warranty, claims submitted for payment must adhere to the Audi Warranty Policies and Procedures Manual. The TSB specifies the following details for warranty claims:

• Claim Type: If the vehicle is outside of any warranty, this Technical Service Bulletin is informational only.
• Service Number: 2470
• Damage Code: 0055
• Labor Operations: GFF (0150 0060 for time stated on diagnostic protocol) and GFF (0150 0010 with associated operations).
• Claim Comment: As per TSB 2078914/2

Important Warnings for Owners

Owners should be aware that if their vehicle is no longer covered by Audi's warranty, this Technical Service Bulletin serves as informational guidance only. This means that the cost of diagnosis and repair for the Audi P064F00 MIL on issue may not be covered by the manufacturer.

What Owners Should Do

If your 2025-2026 Audi A5, S5, SQ5, or A6 is exhibiting symptoms such as the "MIL/ Exhaust emission warning lamp is on." or the "Engine does not start," and you suspect DTC P064F00, it is recommended to contact an authorized Audi dealership. Provide them with the symptoms you are experiencing and mention Technical Service Bulletin 2078914/2. The dealership technicians have the necessary tools and updated procedures to perform the virtual ECM replacement and coding to resolve the issue.

NHTSA ID: 11025316