2025 Audi A5 Multiple Driver Assist Systems Offline TSB

Owners of 2025 Audi A5, Q5, SQ5, and S5 vehicles may experience a condition where multiple driver assist systems become unavailable. This issue, detailed in Audi Technical Service Bulletin (TSB) 2077141/4, is linked to software errors in the short-range radar sensors, leading to various warning messages in the instrument cluster and a reduction in vehicle safety features. The problem specifically affects the functionality of systems like exit warning, lane change assist, cross-traffic assist, and automatic emergency braking.

This TSB, released on October 24, 2025, addresses a functional issue related to both software and hardware. It provides guidance for technicians on how to diagnose and resolve the problem, ensuring that the advanced driver assistance systems (ADAS) in affected vehicles operate correctly. The primary solution involves a software update, but in certain circumstances, control unit replacement may be necessary for the 2025 Audi A5 multiple driver assist systems offline condition.

Symptoms

When the 2025 Audi A5 multiple driver assist systems offline condition occurs, drivers will typically notice several warning messages appearing in the instrument cluster. These messages indicate that specific safety and convenience features are either malfunctioning or completely unavailable. It's crucial for owners to understand what these warnings mean for their vehicle's operation.

Common owner-facing messages include:

• "Rear turn assist: fault. You can continue driving. See owner's manual." – This indicates that the system designed to help detect vehicles approaching from the rear when backing up is not working.
• "Lane change assist: fault. You can continue driving. See owner's manual." – This warning signifies that the system assisting with safe lane changes, often using blind spot monitoring, is inoperative.
• "Exit warning system: fault. You can continue driving. See owner's manual." – This message means the system that alerts occupants to approaching traffic when opening doors is not functioning.
• "Rear cross-traffic assist: fault. You can continue driving. See owner's manual." – Similar to rear turn assist, this indicates a failure in the system that warns of traffic crossing behind the vehicle when reversing.
• "Proactive occupant protection: currently restricted. See owner's manual." – This suggests that the vehicle's pre-collision safety measures, which might include pre-tensioning seatbelts or closing windows, are limited.
• "Active front assist: currently unavailable. See owner's manual." – This critical warning indicates that the automatic emergency braking (Front Assist) system, designed to prevent or mitigate frontal collisions, is not operational.

These symptoms collectively point to a significant impairment of the vehicle's ADAS capabilities, which can impact driving safety and convenience. The underlying cause for these warnings is often a software error in the radar sensors.

Fault Codes / DTCs

When diagnosing the 2025 Audi A5 multiple driver assist systems offline issue, technicians will find specific Diagnostic Trouble Codes (DTCs) stored in the vehicle's event memory. These codes pinpoint the exact nature of the software error within the short-range radar system.

The primary DTC associated with this condition is:

Diagnostic Trouble Code	Fault Symptom	Storage State
C12BFF2	Radar sensors Software error detected	Intermittent

This DTC, specifically with symptom number 1289, can be found in various diagnostic addresses related to the short-range radar units and their corresponding control units:

• 810C - Short-range radar 4: Associated with control units -J769-/-J770- (Short-Range Radar 3 & 4).
• 8109 - Short-range radar 1: Associated with control units -J1088-/-J1089- (Short-Range Radar 1 & 2).
• 810A - Short-range radar 2: Also associated with control units -J1088-/-J1089-.
• 810B - Short-range radar 3: Also associated with control units -J769-/-J770-.

These diagnostic addresses correspond to the physical radar control units responsible for object detection and lane change assist functions. The TSB notes that software versions 0560 and 0579 are relevant to these control units.

Important Warnings and Notices

Audi has issued specific notices regarding the diagnosis and resolution of this issue:

• Ignorable DTC: "The event memory entry 'C12BFF2: Radar sensor software error detected' (symptom number 1282) does not lead to a customer complaint and can be ignored. NO measures are necessary." This is crucial for owners and technicians, as it prevents unnecessary repairs for a specific symptom number of the C12BFF2 code.
• Phased Software Release: "The combined software update described in TSB 2079690 will be released in stages for the individual vehicle models/markets, depending on availability." This means the software fix may not be immediately accessible for all vehicles, and owners should consult their dealership for current availability.

Diagnosis and Trigger Conditions

The 2025 Audi A5 multiple driver assist systems offline condition is reproducible and is confirmed when the DTC "C12BFF2: Radar sensor software error detected (symptom number 1289)" is stored in the event memory. This indicates a functional issue related to both the software and hardware of the short-range radar system. The fault can be found in the Short-Range Radar 3 & 4 control units (-J769-/-J770-) and the Short-Range Radar 1 & 2 control units for object detection (-J1088-/-J1089-).

Repair Procedure Summary

The repair for the 2025 Audi A5 multiple driver assist systems offline condition, as outlined in TSB 2077141/4, involves two potential approaches depending on the availability of a specific software update:

1. Software Update (Preferred Method): Technicians must first check if TSB 2079690, titled "00 Combined software update 03.10.00/C (28.13.01) KD2", is visible and applicable for the vehicle. If it is, the combined software update described in TSB 2079690 should be performed. This update is designed to resolve the underlying software error causing the radar sensor malfunction.

2. Control Unit Replacement (If Software Update Unavailable): If the combined software update (TSB 2079690) is not yet available for the specific vehicle model or market, and the event memory entry "C12BFF2: Radar sensor software error detected (symptom number 1289)" is logged, then the relevant short-range radar control unit(s) must be replaced. This includes:

   • The "Short-Range Radar 3 & 4" control unit, also known as -J769-/-J770- (diagnostic address 810B/810C), which is involved in lane change assist.
   • The "Short-Range Radar 1 & 2" control unit, also known as -J1088-/-J1089- (diagnostic address 8109/810A), which handles front left/right radar sensor object detection.

Revision History of TSB 2077141/4

This Technical Service Bulletin has undergone several revisions to refine its scope and instructions:

• Revision 4: Updated to include revised warranty information, specifically regarding KD2 flash details.
• Revision 3 (October 17, 2025): The header was revised to add specific models, and the service section was updated to include a reference to the KD2 update.
• Revision 2 (July 17, 2025): The header was revised to reflect updated models and customer codes. The service section was also updated to include a statement concerning launch vehicles.

Warranty Information

Audi provides specific guidelines for warranty claims related to TSB 2077141/4:

• Claim Type: If the vehicle is outside of its warranty period, this Technical Service Bulletin is for informational purposes only.
• Service Numbers: The service numbers associated with this TSB are 9635 (for -J769-/-J770- control units) and 9158 (for -J1088-/-J1089- control units).
• Damage Code: The damage code to be used for claims is 0039.
• Labor Operations: Specific labor operations and time units (TU) are allocated for the repair:
  • For Software Update (TSB 2079690, Combined software update "03.10.00/C (28.13.01) KD2"):
    • Software update, including connecting battery charger: Operation code 0151 0010 (Refer to SRT for associated operations).
    • Fixed rate for software update, covering all required preliminary and follow-up work (including bus sleep cycle, calibration drive, and additional work if flashing is aborted): Operation code 0151 0040 (130 TU).
  • For Parts Replacement:
    • Remove and install object detection control unit: Operation code 9158 1960 (Refer to SRT for associated operations).
    • Remove and install 2 object detection control units: Operation code 9158 2060 (Refer to SRT for associated operations).
    • Remove and install lane change assist control unit: Operation code 9635 1950 (Refer to SRT for associated operations).
    • Remove and install 2 lane change assist control units: Operation code 9635 2050 (Refer to SRT for associated operations).
    • GFF / Guided Functions: Operation code 0150 0060 (Time stated on the diagnostic protocol).
• Claim Comment: All claims should include the comment "As per TSB 2077141/4".
• Billing Note: When performing the combined software update, time stamps are not required for billing under warranty. This allows for other work to be performed concurrently and permits non-productive personnel to execute the update.

Owner Action

If you own a 2025 Audi A5, Q5, SQ5, or S5 and are experiencing warning messages related to your driver assist systems, such as "Lane change assist: fault" or "Active front assist: currently unavailable," you should contact your authorized Audi dealership. Inform them about the 2025 Audi A5 multiple driver assist systems offline issue and mention Technical Service Bulletin 2077141/4. Your dealer will be able to diagnose the specific fault codes, determine if the combined software update (TSB 2079690) is available for your vehicle, or proceed with the necessary control unit replacement.

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Source: NHTSA ID: 10250917