2019-2024 Audi e-tron Mean Cell Voltage Test Failure

Symptoms

Owners of 2019-2024 Audi e-tron vehicles may experience an issue during diagnostic procedures. Specifically, the "008C – Determine mean cell voltage function test plan", also known as the "AX2 - High-Voltage Battery 1 mean cell voltage test", will not complete successfully. Instead, the diagnostic tool will display the error message: "The vehicle could not be clearly detected". This indicates a problem with the Audi e-tron mean cell voltage test.

Diagnosis / Trigger Conditions

This diagnostic failure occurs because the ODIS Service diagnostic program loses connection with the vehicle during the 008C mean cell voltage test. While communication with the battery control unit initially works, the PR number recognition on some vehicles is not functioning correctly. This prevents the diagnostic test from proceeding and leads to the diagnostic tool displaying the error message. The issue is specific to the 2019-2024 Audi e-tron models.

Important Warnings

Audi has issued critical instructions regarding the installation and removal of this hotfix:

• Installation: "We recommend installation of this hotfix on one diagnostic device ONLY." This ensures that the hotfix does not interfere with other diagnostic systems.
• Removal: "Hotfix must be removed immediately after performing the procedure." Failure to follow this instruction "will cause other vehicle diagnostics sessions to malfunction."

Service Procedure Summary

To resolve the failing Audi e-tron mean cell voltage test, technicians must download, install, and then uninstall a specific hotfix for the ODIS Service diagnostic system. The required ODIS software version for this hotfix is Audi brand version 2.37.7, and the hotfix number is A_2.37.7_PR_NUMBER_20250417-133907.

1. Download Hotfix

1. Open a web browser on the diagnostic device and log on to AccessAudi.com.
2. Navigate to Elsa2Go > Service References > Software/Hardware Updates.
3. Search for the "AOS-25-21 PR Number Hotfix Zip File".
4. Click the zip file to download it and save it to the Windows desktop.
5. Close the browser.
6. Browse to the desktop and double-click the downloaded zip file (e.g., AOS-25-21-PR Number Hotfix Zip File) to open it.
7. Right-click the hotfix file name inside the zip archive (e.g., V_2.49.8_HF_FSC_20240229-100911) and select 'Copy'.
8. Right-click anywhere on the Windows desktop and select 'Paste'. A file icon (e.g., V2.47.7_OCC_002019) should now appear on the desktop.

2. Install Hotfix into ODIS Service

1. Open ODIS Service, ensuring it's run as an administrator.
2. Expand the 'Data' submenu within ODIS.
3. Under the 'Hotfix' section, click 'Download'.
4. When prompted with "Should the workshop data patch be imported?", click 'Continue'.
5. A directory selection window will appear. Browse to and highlight the hotfix file that was pasted to the desktop, then click 'Select Folder'.
6. Once the installation is complete, a message will confirm "Workshop data patch was completed successfully." Click 'OK'.
7. Proceed to perform the diagnostic procedure, specifically the Audi e-tron mean cell voltage test (008C).

3. Uninstall Hotfix from ODIS Service

1. After completing the diagnostic procedure, return to the 'Hotfix' section in ODIS Service.
2. Select 'Erase'.
3. When prompted with "Should the active workshop patch be deleted?", click 'Continue'.
4. A confirmation message "The workshop data patch was erased." will appear. Click 'OK'.
5. Close ODIS Service.

Required Software

• ODIS Service diagnostic software (Audi brand version 2.37.7)
• Hotfix file: A_2.37.7_PR_NUMBER_20250417-133907

Owner Action

If you own a 2019-2024 Audi e-tron and your vehicle requires a diagnostic check involving the high-voltage battery, be aware of this potential issue. Your Audi service center is equipped with the necessary hotfix (AOS-25-21) to ensure accurate diagnosis. There is no direct action required from owners other than taking your vehicle to an authorized Audi dealership for service.

NHTSA Source: AOS-25-21