Audi A6, S6, RS6 & allroad Seat Memory Module: Fixing Failures & Replacement Guide (1998-2005)

Symptoms of a Failing Seat Memory Module

When the driver's seat memory module begins to fail in a 1998-2004 Audi A6, 2001-2005 Audi allroad, 2002-2003 Audi S6, or 2003-2004 Audi RS6, the symptoms can range from a minor annoyance to a completely non-functional seat. Because the module controls all electronic seat functions, its failure can manifest in several ways.

• Complete Seat Failure: The most obvious symptom is when the seat stops responding to any inputs from the adjustment switches on its side.
• Memory Function Loss: The seat may still be adjustable using the regular controls, but it will not save new positions or recall previously saved ones using the door buttons.
• Intermittent Operation: The seat may work one day and not the next. This can sometimes be related to temperature or moisture levels in the cabin.
• Erratic Movement: Pressing a memory button might cause the seat to move to an incorrect position or stop halfway.
• Clicking Noises: You may hear clicking from under the seat as the module's internal relays try to engage but fail to send power to the motors.
• No Communication with Diagnostic Tools: When using a tool like VCDS, the module at address 36 (Seat Mem. Drvr) may not respond or may show specific fault codes.

Common Diagnostic Trouble Codes (DTCs)

A diagnostic scan using a tool like VAG-COM (VCDS) can reveal specific codes pointing to a faulty module or its wiring. Common codes include:

• 01191 - Motors for seat adjustment, Short Circuit.
• 65535 - Control Module Malfunction (Internal Failure).
• 16347 - Control Module - EEPROM Error.
• 00461 - Control Module for Seat Memory; Passenger (J521) - No Signal/Communication.

Known Issues: Water Intrusion is the #1 Killer

The primary cause of failure for this module is not typically old age, but water damage. The module is located in a vulnerable position underneath the driver's seat, and the C5 platform is known for developing water leaks into the cabin. When water soaks the carpet, it pools around the module, causing corrosion on its electrical connectors and circuit board.

If you are replacing this module, it is critical to find and fix the source of the water leak. Otherwise, your replacement module will likely fail for the same reason. Common leak points on the Audi A6, S6, RS6, and allroad include:

• Clogged Cowl/Battery Drains: The area under the battery in the engine bay has drain holes that get clogged with leaves and debris. When they clog, rainwater overflows through the cabin air filter opening and into the passenger footwell, eventually soaking the entire floor.
• Clogged Sunroof Drains: Each corner of the sunroof assembly has a drain tube. If the front tubes become clogged, water backs up and leaks down the A-pillars and into the front footwells.
• Improperly Sealed Windshield Cowl: The plastic trim piece at the base of the windshield must be perfectly seated. If it's loose, water can run directly into the cabin air intake.

Buying a Used Seat Memory Control Module

Buying a used OEM module is a cost-effective way to restore your seat's function. Because these modules rarely fail on their own, a dry, corrosion-free unit from a salvage vehicle is an excellent choice. Here’s what to look for:

• Match the Part Number: The primary part numbers are 4B0959760A and 4B0959760B. The 'B' version is a later revision that supersedes the 'A' version; they are interchangeable.
• Physical Inspection: Carefully inspect the electrical connector pins on the used module. Look for any signs of green or white crusty corrosion, which indicates past water exposure. Reject any module that isn't perfectly clean.
• Check the Connectors: Also inspect the wiring harness connectors in your own car. If they are corroded, they must be cleaned thoroughly with an electronics cleaner or replaced before plugging in the new module.
• No Component Protection Worries: A major advantage for these specific vehicles (1998-2005 C5 platform) is that the seat memory module does not use Audi's "Component Protection" anti-theft system. This means you can install a used module without needing a dealer to authorize it, which is a requirement on newer Audis.

Programming and Installation

While this module does not have Component Protection, it is not always a simple plug-and-play swap. You may need a VAG-specific diagnostic tool like VCDS to ensure it works correctly.

Replacement Steps Overview

1. Disconnect the Battery: This is a crucial safety step before working with any vehicle electronics, especially the seat's airbag system.
2. Access the Module: The module is located under the driver's seat. If the seat motors still work, move the seat all the way up and back to access the front mounting bolts. If the seat is stuck, accessing the bolts is more difficult but still possible.
3. Remove Seat Bolts: Remove the bolts holding the seat rails to the floor. You can then carefully tilt the entire seat backward to access the wiring and module underneath without fully removing it from the car.
4. Swap the Module: The module is held in a bracket under the seat. Disconnect the electrical connectors, unbolt it, and swap in the replacement unit.
5. Reconnect and Test: Reconnect the seat wiring and the battery. Test all seat functions, including memory.

Coding and Adaptation with VCDS

In many cases, the replacement module will work immediately. However, if the memory functions are not working correctly after installation, you may need to perform a coding or adaptation procedure.

• Basic Settings Reset: Sometimes, simply running the seat through its full range of motion in every direction (all the way forward, back, up, down, and recline) can re-calibrate the module's position sensors.
• VCDS Coding: Connect to the car with VCDS and go to control module 36 - Seat Mem. Drvr. Check for fault codes. You may need to verify the module's software coding matches your car's options (e.g., with or without power steering column adjustment). It's helpful to have a scan from before the original module failed, but often the coding from the used module will work fine.

Cost of Replacement

Replacing the seat memory module can be very expensive at a dealership, but much more affordable as a DIY project with a used part.

Frequently Asked Questions (FAQ)