2021-2024 Audi A4, S4 Rear Window Reverses DTC B14874B

Important Warning

This Technical Service Bulletin (TSB) specifically addresses situations where DTC B14874B ("Motor for window regulator excess temperature") is stored in the door module. It is important to note that this TSB does not relate to situations where B148754 Motor for window regulator no basic setting (Static) is stored upon initial scan of the vehicle. For concerns related to B148754, different repair procedures may be necessary.

Symptoms

Owners of 2021-2024 Audi A4, A4 allroad, and S4 models may notice that one or both rear windows cannot be closed using the one-touch feature. Instead, the window reverses direction immediately when the upper stop is reached. This indicates a malfunction in the window's operation, preventing full closure with a single press of the switch.

Fault Codes / DTCs

When diagnosing this issue, technicians may find the following Diagnostic Trouble Code (DTC) stored intermittently in the left rear door module (-J388-) or right rear door module (-J389-), which correspond to diagnostic addresses 00BB or 00BC:

• DTC B14874B: Motor for window regulator excess temperature.

This DTC points to a software-related issue within the door module that causes the window regulator motor to report an excess temperature condition, leading to the window's reversal behavior.

Diagnosis / Trigger Conditions

The root cause of the Audi A4 rear window reverses B14874B issue is identified as a software problem within the door module. This software anomaly can lead to incorrect readings or responses from the window regulator motor, triggering the safety feature that reverses the window's direction upon sensing an obstruction or fault, even when none is present.

Repair Procedure Summary

The repair for the Audi A4 rear window reverses B14874B fault involves a power reset of the affected door module(s). This procedure aims to clear the software glitch without requiring part replacement. The steps are as follows:

1. Fuse Removal: Locate fuse carrier C (black) and remove fuses 7 and 11. These fuses supply power to the two rear door modules.
2. Wait Period: Allow at least 2 minutes to pass after removing the fuses. This ensures a complete power discharge from the door modules.
3. Fuse Reinsertion: Reinsert fuses 7 and 11 back into fuse carrier C.
4. Basic Settings Reset (if needed): If the basic settings for the window regulator were lost during the power reset, they must be re-established. This can be done using a shop tester or by manually pulling the window regulator switches upwards for approximately 2 seconds immediately after closing the windows manually.
5. Fault Clearing: Clear all stored fault codes from the vehicle's system.
6. Re-evaluation: Test the rear windows to ensure they now operate correctly with the one-touch feature and no longer reverse direction at the upper stop.

Required Tools

To perform the diagnostic and repair procedures outlined in TSB 2070094/2, technicians will require specific tools:

• VAS 6160 / VAS 6150: These are VAS testers equipped with the current version of ODIS (Offboard Diagnostic Information System) running on Windows 10. These tools are essential for reading and clearing fault codes, as well as performing basic settings adjustments if necessary.

Warranty Information

This Technical Service Bulletin provides specific guidelines for warranty claims related to the Audi A4 rear window reverses B14874B issue:

• Claim Type 110: Applicable for vehicles up to 48 months or 50,000 miles.
• Claim Type G10: For Audi Certified Pre-Owned (CPO) vehicles; ownership verification is required.
• If the vehicle is outside of any warranty coverage, this TSB serves as informational guidance only, and any repairs would typically be at the owner's expense.
• Service Number: 6438
• Damage Code: 0040
• Labor Operations: Reset door module (Labor Operation 6438 4199, 20 Time Units (TU)).
• Diagnostic Time: GFF (0150 0000, up to a maximum of 100 TU, as stated on the diagnostic protocol).
• No allowance is provided for road tests before or after the service procedure.
• All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual, and are subject to audit by Audi Warranty.

Owner Action

If your 2021-2024 Audi A4, A4 allroad, or S4 is exhibiting the symptom of a rear window reversing direction at the upper stop, especially if you suspect the Audi A4 rear window reverses B14874B fault, it is recommended to schedule an appointment with an authorized Audi service center. They have the necessary diagnostic tools and expertise to confirm the DTC and perform the door module power reset as described in TSB 2070094/2.

---

NHTSA ID: 10242953