2021-2025 Audi Q5 e / A7 e Electrical System Fault

Audi has released a Pending Service Solution (PSS) bulletin, identified as 93 PSS and Transaction No. 2079460/1, addressing an Audi Q5 e electrical system fault affecting certain 2021-2025 Audi Q5 e and 2021-2022 Audi A7 e Plug-in Hybrid Electric Vehicles (PHEV). This bulletin, released on October 2, 2025, outlines a known software issue that can lead to the vehicle being unable to start and displaying critical warning messages.

This communication serves as an interim measure, acknowledging the problem while a permanent software solution is still under development. It provides a temporary workaround and crucial advice for technicians and vehicle owners regarding diagnosis and component replacement.

Symptoms Owners May Notice

Owners of affected Audi Q5 e and A7 e models may experience a significant Audi Q5 e electrical system fault that prevents the vehicle from starting. A prominent warning message will appear in the instrument cluster, stating: "electrical system: fault Safely stop vehicle". This direct message indicates a critical issue requiring immediate attention, impacting the vehicle's operational status.

Fault Codes / DTCs

When diagnosing the Audi Q5 e electrical system fault, technicians will typically find specific Diagnostic Trouble Codes (DTCs) stored in the hybrid battery management control unit, identified as J840 (address word 008C). These codes pinpoint the nature of the communication or performance issue within the high-voltage system:

• U029A00: This code indicates a "Lost communication with Hybrid/EV Battery Pack Sensor Module." It suggests that the main control unit is not receiving expected data from the battery pack's sensor module, which is crucial for monitoring battery health and safety.
• U059B00: This DTC signifies "Invalid Data Received From Hybrid/EV Battery Pack Sensor Module." Unlike a complete loss of communication, this code implies that data is being received, but it is corrupted or outside expected parameters, potentially leading to incorrect system operation.
• P0B3400 (Symptom ID: 40975): This code points to "High Voltage Service disconnect Circuit Performance." This indicates an issue with the circuit responsible for safely disconnecting the high-voltage system, which is a critical safety feature in hybrid vehicles.

Technical Background and Production Solution

Audi has identified the root cause of this Audi Q5 e electrical system fault as a software issue within the vehicle's systems. This means the problem is not due to a faulty hardware component but rather an error in the programming that governs the hybrid battery management. As of the bulletin's release, a permanent software solution is still under development. Audi anticipates that a definitive fix will be available by the end of the 3rd quarter of 2026, though this timeline is subject to change.

Important Warnings for Owners and Technicians

This bulletin includes critical advisories to prevent unnecessary repairs and costs:

• "Do not replace any components for this condition since this will not resolve the customer's concern." This instruction is vital, as replacing parts like the hybrid battery management module or related high-voltage components will not fix the underlying software issue and would result in wasted expense and effort.
• If the vehicle's condition matches the description in the bulletin, owners should be informed that "no repairs are necessary at this point." Instead, a temporary procedure is available, and a permanent solution is expected in the future.

These warnings emphasize that the current issue is software-based, and hardware replacement is not the correct course of action.

Temporary Repair Procedure Summary

While a permanent software update is being developed, Audi provides a temporary procedure to rectify the Audi Q5 e electrical system fault if both the customer complaint and workshop findings (specifically the presence of the listed DTCs) apply. This procedure involves cycling power to a specific fuse to reset the safety circuit and interrupt the contactors' 12-volt control circuit. The steps are as follows:

1. De-energize the High Voltage System: Technicians must first safely de-energize the high-voltage system according to the procedures outlined in ELSA (Electronic Service Information System). This is a critical safety step to prevent electrical shock during service.
2. Remove Fuse AX1: Locate and remove the fuse designated AX1. This fuse is specific to the A7 PHEV SN10 and Q5 PHEV SF11 models, controlling a part of the high-voltage system.
3. Wait: Allow a minimum of one minute to pass after removing the fuse. This ensures that any residual power is dissipated and the system fully resets.
4. Re-install Fuse AX1: Insert the AX1 fuse back into its original position.
5. Re-energize the High Voltage System: Following the re-installation of the fuse, the high-voltage system must be safely re-energized using the procedures detailed in ELSA.

This temporary measure aims to clear the fault condition and allow the vehicle to operate normally until the permanent software solution becomes available.

Warranty Information

For vehicles still under warranty, claims related to this Audi Q5 e electrical system fault should be submitted in accordance with the Audi Warranty Policies and Procedures Manual. The bulletin specifies the following details for warranty claims:

• Service Number: 9327
• Damage Code: 0039
• Labor Operations: Specific labor codes are provided for the diagnostic and temporary repair steps:
  • Repair high-voltage battery (remove fuse): Labor operation 9303 4199, allocated 10 Time Units (TU).
  • GFF (Guided Fault Finding): Labor operation 0150 0010, referencing the Service Repair Time (SRT) with associated operations.
  • De-activate and activate high-voltage system: Labor operation 9310 8350, referencing the SRT with associated operations.
  • GFF (Guided Fault Finding): Labor operation 0150 0060, where the time is stated on the diagnostic protocol.
• Claim Comment: Claims should include the comment "As per TSB 2079460/1" to link them directly to this bulletin.

If the vehicle is outside of warranty, this Technical Service Bulletin is for informational purposes only, meaning any diagnostic or repair costs would typically be borne by the owner. However, given the nature of a known software issue and a pending solution, owners may wish to discuss options with their Audi dealership.

Owner Action

If your 2021-2025 Audi Q5 e or 2021-2022 Audi A7 e displays the "electrical system: fault Safely stop vehicle" message or exhibits starting issues, and especially if accompanied by the DTCs U029A00, U059B00, or P0B3400, contact your authorized Audi dealership. Inform them about the symptoms and reference Audi Transaction No. 2079460/1 (93 PSS). The dealership can perform the temporary repair and ensure your vehicle's condition is documented in the PSS application, which is crucial for tracking and for future application of the permanent software solution when it becomes available.

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Source: NHTSA ID: 11025248