2025 Audi A5 Battery Drain and Unlocking Issue TSB

Owners of certain 2025 Audi A5, Q5, SQ5, and S5 models may experience a frustrating issue where their vehicle's battery drains unexpectedly, making it impossible to unlock the car using the remote control. This problem, identified in Technical Service Bulletin (TSB) 2078848/1, specifically occurs when the vehicle is in active transport mode.

Symptoms

The primary symptoms reported by owners include the vehicle being unable to be unlocked with the remote control. This is a direct consequence of the vehicle battery being completely flat. The underlying issue is described as "Vehicle cannot be unlocked - battery drained on vehicle in active transport mode", with complaint types noted as "functionality -> cannot be opened" and "electrical -> voltage too low". If you are experiencing a 2025 Audi A5 battery drain, these are the key indicators.

Technical Background

According to Audi, the root cause of this 2025 Audi A5 battery drain issue is a software error within the dedicated short-range communication aerial, which corresponds to diagnostic address 8136. When the locking sensor on the driver's door is touched while the vehicle is in transport mode, this software error can lead to an unintended no-load current draw. This continuous draw can discharge the battery within a few days. Transport mode is designed to deactivate temporarily each time the vehicle is started and reactivate when the engine is switched off.

Diagnosis

To diagnose this specific battery drain condition, technicians are instructed to check history data 5, which pertains to the energy-critical status, and history data 66, which contains sleep inhibitor information. These checks are performed as follows:

1. History Data 5 (Diagnostic Address 0019): Read this data using the appropriate test program. If a no-load current of approximately 1.5A is observed, it indicates that this TSB likely applies.
2. History Data 66 (Diagnostic Address 8124): Retrieve this data, which shows up to five blocks with different timestamps. Technicians should look for the measured value "Watchdog time to control unit 1". If this value is 255, it signifies that a control unit kept the data bus awake for more than 255 minutes.
3. Identifying the Culprit Control Unit: Above the "Watchdog time to control unit 1" value, there is a measured value labeled "Control unit with longest watchdog time". If this value is 279, it confirms that the dedicated short-range communication aerial (diagnostic address 8136) is the component causing the extended wake-up time and subsequent battery drain. This TSB is applicable only if these specific values are recorded in history data 5 and 66.

Important Warnings for Owners

Audi has provided critical advisories, especially for vehicles still in transport mode:

• The contact protection (blue foam pad) on the driver door should only be removed after deactivating transport mode.
• The door handle of the driver's door must not be touched when you switch off the engine. Ensure no one else touches it accidentally, such as by hanging an arm out of an open window while parking. If the handle is touched, restart the engine and switch it off again without touching the driver door handle.
• When restoring the vehicle's power supply, always follow the correct sequence for disconnecting and connecting the emergency power supply/battery, as detailed in the vehicle Owner's Manual.
• If the battery is no longer in its delivered condition, it must be replaced.

Repair Procedure Summary

The long-term solution implemented in production for the Audi A5 began with software version 0600 in week 04/2025. For the Audi A6 e-tron, software version 0601 was implemented in week 25/2025. As an immediate factory measure, contact protection (a blue foam pad) is fitted to the door handle. For vehicles already affected by the 2025 Audi A5 battery drain, the repair involves confirming the diagnostic values as described above. If confirmed, the service procedure involves Guided Fault Finding (GFF) operations. For vehicles without battery replacement, the labor operations are 0150 0010 and 0150 0060. If battery replacement is necessary, additional labor operation 2706 19xx for battery removal and installation is included, followed by GFF operation 0150 0060.

Warranty Information

This Technical Service Bulletin (TSB 2078848/1) is informational only if the vehicle is outside of warranty. The Service Number associated with this issue is 9688, and the Damage Code is 0039. All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual.

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Source: NHTSA ID: 11022652