Genuine OEM N91084501 - Transmission Filter Housing O-Ring

Product Overview

The Genuine OEM N91084501 is a transmission filter housing O-ring designed for Audi and Volkswagen models from 2006 onward. This small but critical seal maintains proper fluid containment within the transmission filter housing, preventing leaks that could compromise transmission performance and fluid levels. The O-ring fits Audi A3, TT, TTS, RS3, and S3 models, as well as select Volkswagen Passat and Eos variants across multiple generations. As a Genuine OEM part, it meets factory specifications and is backed by Audi and Volkswagen dealership warranty coverage.

This O-ring is a single replacement component. Verify your transmission filter housing service kit contents before ordering to confirm whether additional seals or gaskets are needed for your complete service.

Symptoms of a Failing Transmission Filter Housing O-Ring

• Red or pink transmission fluid visible beneath the vehicle or around the transmission filter housing area.
• Low transmission fluid level on the dipstick despite no visible leaks elsewhere.
• Transmission fluid odor inside the vehicle cabin or engine bay.
• Gradual transmission fluid loss between services.
• Transmission overheating due to reduced fluid volume.

Cross Reference Numbers

This Genuine OEM N91084501 is equivalent to the following part number: N910845-01.

Vehicle Compatibility

This part fits the popular models below. For Fitment Confidence, please use the vehicle selector tool above to verify exact compatibility for your vehicle.

• Audi A3 2.0 L4 Gas (8P): 2006–2013
• Audi A3 3.2 V6 Gas Quattro (8P): 2006–2008
• Audi A3 1.8 L4 Gas (8V): 2015–2018
• Audi A3 2.0 L4 Gas Quattro (8V): 2015–2020
• Audi A3 2.0 L4 Diesel (8P): 2010–2013
• Audi A3 2.0 L4 Gas (8V): 2017–2019
• Audi S3 2.0 L4 Gas (8V): 2015–2020
• Audi RS3 2.5 L5 Gas (8V): 2017–2020
• Audi RS3 2.5 L5 Gas (8Y): 2022–2025
• Audi TT 2.0 L4 Gas (8J): 2008–2014
• Audi TT Quattro 2.0 L4 Gas (8J): 2008–2015
• Audi TTS Quattro 2.0 L4 Gas (8J): 2009–2013
• Volkswagen Passat 3.6 V6 Gas (NMS): 2012
• Volkswagen Eos 2.0 L4 Gas: 2013
• Volkswagen GTI 2.0 L4 Gas (MK6): 2008

This may also fit other applications. Please use the vehicle selector tool to verify fitment.

Often Replaced Together

For a complete transmission filter service, many owners replace the following at the same time:

• Transmission filter element (main filter cartridge).
• Transmission fluid (full or partial drain and refill per service interval).
• Additional transmission housing gaskets or seals if visible wear is present.

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Frequently Asked Questions

How do I know if my Audi A3 or TT transmission filter housing O-ring is failing?

The most common sign is red or pink transmission fluid pooling beneath your vehicle or visible around the transmission filter housing. You may also notice a gradual drop in transmission fluid level on the dipstick without obvious leaks elsewhere, or a burnt transmission fluid smell. If you catch the leak early, the O-ring replacement is straightforward and prevents more costly transmission damage.

What is the difference between this O-ring and the transmission filter itself?

The O-ring seals the transmission filter housing to prevent fluid from leaking around the housing perimeter. The filter element itself removes contaminants from the fluid. Both can wear over time, and both are commonly replaced during transmission service. The O-ring is typically much less expensive than the filter, but it is equally important for maintaining a sealed system.

How long does it take to replace the transmission filter housing O-ring?

Replacement time varies depending on your vehicle's engine bay layout and transmission type, but most technicians complete the job in 30 minutes to 1 hour. You will need a floor jack, jack stands, a socket set, and potentially a transmission filter wrench to remove the old housing. Consult your service manual for the exact procedure and any special tools specific to your model year.

Can I replace just the O-ring, or should I replace the entire filter housing?

In most cases, you can replace the O-ring alone. However, if the housing itself shows cracks, corrosion, or thread damage, replacement of the entire assembly may be necessary. Inspect the housing carefully during removal. If it appears intact, the O-ring replacement will restore the seal. If you see damage, order a replacement housing as well to avoid repeat leaks.

Is this Genuine OEM part better than an aftermarket O-ring?

Genuine OEM parts are manufactured to Audi and Volkswagen factory specifications and meet strict quality standards. They are also backed by dealership warranty coverage. Aftermarket O-rings may be cheaper but can vary in material quality and durability. For a critical seal like this, a Genuine OEM part provides confidence that the replacement will perform as designed and last through your vehicle's service life.

How often should I replace the transmission filter housing O-ring?

There is no fixed replacement interval for the O-ring itself. It is typically replaced only when it fails or during a transmission filter service if wear is visible. However, if you are performing transmission service regularly and the O-ring has been in place for many years, consider replacing it as a preventive measure to avoid future leaks. Refer to your manufacturer's service documentation for recommended transmission maintenance schedules.

Order Genuine OEM N91084501 today. In-stock orders ship same or next business day from our U.S. warehouse, and our fitment team is one call away if you need help confirming the right part for your Audi or Volkswagen.

Note: All information on this page and in the FAQ is for general reference only. Verify fitment and consult a professional as needed. eEuroparts.com is not responsible for incorrect part selection or installation.