2021 Audi Rear Window Defogger Not Operational TSB

If you own a 2021 Audi and are experiencing an issue where your rear window defogger fails to operate, you're not alone. Audi has issued Technical Service Bulletin (TSB) 2058452/3 to address this specific problem. This TSB provides a detailed solution for the Audi rear defogger issue, ensuring your vehicle's rear visibility system functions correctly.

Symptoms

Owners of affected Audi vehicles will notice a clear symptom: "The rear window defog button will light up for a second when pressed, then immediately turn off." This indicates that the system is not engaging as expected. Importantly, workshop findings indicate that no diagnostic trouble codes (DTCs) are typically stored in the vehicle's system when this problem occurs, making it harder to diagnose without specific knowledge of this TSB.

Technical Background

The root cause of this Audi rear defogger issue lies within the comfort system central control module, identified as J393 (address word 0046). This module can become locked in a software loop, preventing the rear window defogger from activating properly. This software malfunction requires a specific intervention to reset and restore normal operation.

Production Solution

Audi's production solution involves an updated software version for the comfort system central control module, J393. This update is designed to resolve the software loop condition, allowing the rear window defogger to function as intended.

Repair Procedure Summary

Addressing the Audi rear defogger issue involves a series of steps performed by a qualified technician:

1. Verify the Concern: The technician will first attempt to reproduce the customer's reported concern. It's important to note that for the rear window defogger to operate, the ambient temperature must be less than 95°F (35°C), and the engine must be running. If the concern cannot be duplicated under these conditions, the TSB may not apply.
2. Check Control Module Part Number: Using the ODIS diagnostic system, the part number of the comfort system central control module, J393 (address word 0046), will be checked. If the existing part number begins with "8W0," the module must be replaced with a superseded "8W1" part number. Technicians are advised to consult the parts catalog for the latest available part numbers.
3. Software Management Instructions: All instructions detailed in TSB 2011732: 00 Software Version Management (SVM), operating instructions, must be followed. This ensures proper handling of software updates.
4. Software Update: If necessary, the comfort system central control module, J393 (address word 0046), will be updated using the appropriate SVM action code, such as 46A031, as listed in the TSB's detailed tables.

Required Parts and Tools

To perform this repair, technicians may need the following:

• Comfort system central control module: Part Number 8W1907064* (if replacement is necessary).
• ODIS diagnostic system: For checking part numbers and performing software updates.
• Access to the latest parts catalog.
• Reference to TSB 2011732 for SVM operating instructions.

Warranty Information

This repair for the Audi rear defogger issue is covered under specific warranty conditions:

• Standard Warranty: Applicable for vehicles up to 48 months or 50,000 miles.
• CPO Coverage: Certified Pre-Owned (CPO) vehicles are covered under the G10 program.
• Out-of-Warranty: If your vehicle falls outside these warranty parameters, this Technical Service Bulletin serves as informational guidance only, and repair costs may apply.

The following codes are used for warranty claims:

• Service Number: 5789
• Damage Code: 0039
• Labor Operations:
  • Software Update: 0151 0000
  • Comfort system central control module replacement: 5789 55XX
• Claim Comment: As per TSB #2058452/3

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Source: NHTSA ID 10203478