2021-2023 Audi e-tron Electric Motor Leak P0AA600 TSB

Audi Technical Service Bulletin (TSB) 2073858/9 addresses a critical issue affecting 2021-2023 Audi e-tron vehicles: various warning messages in the instrument cluster, specifically related to an electric motor coolant leak and Diagnostic Trouble Code (DTC) P0AA600. This TSB provides guidance for diagnosing and repairing the underlying cause of these warnings.

Owners of affected vehicles may notice a "Drive System/Electrical System Malfunction" message appearing in the instrument cluster. This TSB is crucial for understanding why your Audi e-tron electric motor leaking could trigger these alerts.

Symptoms

Owners may observe a "Drive System/Electrical System Malfunction" message displayed in the instrument cluster. The specific verbatim warning message that may appear is: "Electrical system: malfunction! Safely stop vehicle". This warning might not always be present at the time of vehicle inspection, indicating an intermittent issue.

Other reported symptoms include various noises and vibrations such as jerking, general noise, pinging, misfire, or vibrating sensations. Functionality issues like the vehicle not switching on/connecting or having no function are also noted. Leaks, including those that are not watertight, may also be present.

Fault Codes / DTCs

When diagnosing this issue, workshops may find the following DTC stored in the Battery manager control module -J840- (address word 008C):

• P0AA600: "Hybrid/EV Battery Voltage System Isolation."

This DTC, combined with the observed symptoms, points towards an internal problem with the electric drive system.

Diagnosis and Trigger Conditions

The technical background for this issue indicates that the electric drive motor is damaged due to an internal coolant leak. Workshop findings often include an internal leak, such as a full coolant drip container or coolant leaking from the active chamber on either the front or rear axle of the electric drive motor.

To confirm that the electric drive motor is damaged due to an internal coolant leak, specific conditions must be met. Technicians will inspect for coolant leaks at the rear axle, checking if the drip container is overflowing or empty, and if coolant is leaking from the active chamber. Similar checks are performed for the front axle, looking for coolant leaking from the active chamber.

Important Warnings for Owners and Technicians

Several critical warnings are highlighted in this Technical Service Bulletin:

• Do not operate without coolant: "Vehicles should never be operated without a correctly filled cooling system." Before any work, the seal on the coolant expansion tank should be checked and re-secured.
• Avoid unnecessary parts replacement: "The power electronics must not be replaced if the electric drive motor is leaking." This prevents misdiagnosis and costly, unnecessary repairs.
• Post-repair noise: "If noises from the gearbox noise are apparent after repairs, it can be assumed that incorrect shim was used." This indicates a potential issue with the repair procedure itself.
• Separate billing for control electronics: "If the power and control electronics for electric drive must be replaced as a group, then this must be billed separately (see warranty accounting instructions)."

Repair Procedure Summary

The primary service step involves checking for coolant leaks and localizing the source of the leak. This process includes inspecting both the rear and front axles of the electric drive motor. For the rear axle, technicians will examine the drip container for overflow or emptiness and check for coolant leaking from the active chamber, as illustrated in Figure 2 (showing the drain plug) and Figure 4 (dual motor rear axle drain plug).

For the front axle, the active chamber is inspected for coolant leaks. Figure 3 provides details on the resolver cover and active chamber, noting that a few milliliters of coolant leakage from the resolver cover is not a technical issue, but no coolant should escape from the active chamber bores. The goal is to accurately identify where the Audi e-tron electric motor leaking is occurring to ensure the correct repair.

Owner Action

If you experience a "Drive System/Electrical System Malfunction" warning, see the "Electrical system: malfunction! Safely stop vehicle" message, or suspect your Audi e-tron electric motor leaking, it is crucial to contact an authorized Audi dealership. They have the necessary diagnostic tools and procedures outlined in TSB 2073858/9 to accurately diagnose the issue and perform the required repairs. This issue is typically covered under warranty for eligible vehicles.

Source: NHTSA ID 11022666