2025-2026 Audi A5, S5, A6 Door Lock Malfunction TSB 2079919/2

Owners of certain 2025-2026 Audi A5, S5, and A6 models may experience an intermittent issue where "One of the doors cannot be opened intermittently from the outside." This condition is detailed in Audi Technical Service Bulletin (TSB) 2079919/2, released on December 18, 2025. The TSB outlines diagnostic steps and repair procedures for this specific door lock malfunction.

This TSB, identified as 2079919/2, is a Revision 2 update. It supersedes the initial publication from November 10, 2025, and includes revised conditions and updated warranty labor operations to address the Audi A6 door lock malfunction and similar issues in other affected models.

Symptoms

Owners may notice that "One of the doors cannot be opened intermittently from the outside." While the affected door cannot be opened from the exterior, it can always be opened from the inside. All other doors on the vehicle typically function normally. Interestingly, once the interior door handle of the problematic door has been pulled out, it can often be opened again from the outside.

Fault Codes / DTCs

In some instances, the diagnostic system may log the following fault code in the door control unit for the affected door:

• B122D29 - Lock unit for central locking - implausible signal - passive/intermittent

This DTC is a key indicator for diagnosing the Audi A6 door lock malfunction, but the TSB also provides guidance for situations where this code is not present.

Technical Background

The root cause of this issue is identified as a software and/or hardware problem within the door control unit or the door lock assembly itself. This technical bulletin aims to guide technicians through the correct diagnostic and repair path to resolve the Audi A6 door lock malfunction.

Production Solution

According to the TSB, there is no specific production solution applicable to this issue at the time of publication.

Important Warnings for Owners

Owners should be aware of specific guidelines outlined in TSB 2079919/2. Audi explicitly states, "In this case, replacing parts or attempting repairs will not fix the problem. Unjustified work/replacement parts will be charged back. Invoicing under warranty is not permitted." This means that if the diagnostic steps are not followed correctly, and unnecessary parts are replaced, the costs may not be covered under warranty. If the complaint cannot be reproduced by the technician, the repair might be postponed.

Diagnosis and Repair Procedure Summary

The diagnostic and repair process for the Audi A6 door lock malfunction depends on whether the DTC B122D29 is present.

With DTC B122D29 Present

If the DTC "B122D29 - Lock unit for central locking - implausible signal" is logged, technicians must perform a resistance measurement on the installed door lock. This involves measuring the resistance between pin 2 and pin 4 using a multimeter. To ensure accurate readings, the lock must first be placed into temporary crash redundancy (TCR) mode. This mode is initiated by removing the connector from the lock and firmly pulling the interior door handle twice.

The expected resistance values are:

• Temporary crash redundancy (TCR) (without operating door handles): 1000 ohms
• IDH + TCR (operating interior door handle only): 382 ohms

These measurements have a tolerance of +/- 1% in each case. A measured value of 1000 ohms indicates the lock is in TCR mode, meaning it can only be opened mechanically. If the value is not 1000 ohms, the interior door handle should be pulled twice again as far as the stop, and the measurement repeated. After closing and opening the door, instead of 1000 ohms TCR, an OL (open load) should be measured.

• If the measured values deviate from these specifications, the affected door lock should be replaced.
• If the values correspond to the expected range, technicians should then check the lock wiring according to Guided Fault Finding. If the wiring is confirmed to be in good condition, the door control unit for the faulty door should be replaced.

Without DTC B122D29 Present

If the DTC B122D29 is not logged, but the customer's complaint of the door not opening from the outside can be reproduced, further diagnosis is required. Technicians should check if the issue also occurs when the vehicle is unlocked. If it does, the door control unit on the faulty door should be replaced. If the complaint cannot be reproduced, the repair should be postponed, referring to "The complaint cannot be reproduced" guidelines.

Additionally, technicians are instructed to check for the visibility of TSB 2079690, which details a combined software update (version 03.10.00/C or 28.13.01 KD2). If this software update is applicable to the vehicle, it should be performed as described in TSB 2079690.

Required Tools or Parts

Technicians will require a multimeter to perform the resistance measurements on the door lock. While specific part numbers for the door lock or door control unit are not listed in the TSB, these components would be replaced as needed based on diagnostic findings.

Figures and Diagrams

The TSB includes illustrations (Figure 1, Image 1, Image 2) that show the connectors for the right door lock (labeled 1) and the left door lock (labeled 2). These visuals are crucial for technicians to correctly identify the pins for resistance measurements and to understand the physical layout of the door lock assembly.

Warranty Information

For vehicles outside of any warranty, this Technical Service Bulletin 2079919/2 serves as informational guidance. All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual and are subject to review or audit by Audi Warranty.

Service Numbers and Damage Codes

The damage code associated with these repairs is 0040. Specific service numbers are provided for various repair scenarios:

• 6438: Problem reproduced without DTC "B122D29 - Lock unit for central locking - implausible signal".
• 5717: Front Lock measure / replace.
• 5817: Rear Lock measure / replace.

Labor Operations and Time Units (TU)

Labor Operation Description	Code	Time Units (TU)	Notes
Remove and install front door trim	7059 1900	See SRT	With associated operations
Remove and install rear door trim	7073 1900	See SRT	With associated operations
With DTC B122D29 AND part is 08S or higher AND issue reproduced with door locked/unlocked
Check door locks	5717 0299	10 TU
Check door locks	5817 0299	10 TU
Without DTC B122D29 AND part is 08S or higher AND issue not reproduced
Check door locks	5717 0299	10 TU
Check door locks	5817 0299	10 TU
For software update according to TSB 2079690
Software update, including connecting battery charger	0151 0010	See SRT	With associated operations
Fixed rate for software update, including all required preliminary and follow-up work (including bus sleep cycle, calibration drives, and additional work)	0151 0040	130 TU
In the case of additional attempts
Additional lump sum per flash cancellation	0150 9999	50 TU	Per each documented attempt
With DTC B122D29 AND measure NOK AND part is 07S or lower
Measure door locks	5717 0499	20 TU
Measure door locks	5817 0499	20 TU
Remove and install door lock	5717 1950	See SRT	With associated operations
Remove and install door lock	5817 1950	See SRT	With associated operations
With DTC B122D29 AND measure OK AND part is 07S or lower OR without DTC B122D29 AND part is 08S or higher AND issue only reproduced with door unlocked
Measure door locks	5717 0499	20 TU
Measure door locks	5817 0499	20 TU
Remove and install door control unit	6438 1950	See SRT	With associated operations
After any of the above repair actions are taken
GFF / Guided Functions	0150 0060	Time stated on the diagnostic protocol

When performing the combined software update, time stamps are not required for billing under warranty. Technicians are permitted to work on other vehicles at the same time, and the combined software update can also be performed by non-productive personnel.

Additional Information

All part and service references provided in this TSB (2079919) are subject to change and/or removal. Technicians should always check with their Parts Department and/or ETKA for the latest information and parts bulletins. It is also important to check the Repair Manual for fasteners, bolts, nuts, and screws that require replacement during the repair.

NHTSA ID: 11027414