1998-2005 Audi A6/Allroad, Volkswagen Passat Thermostat Housing 078121121K
OEM Part #: 078-121-121-K (078121121K)
Actual photo
The exact part you’ll receive — not a stock photo.
$38.49
Used
Donor2001 Audi ALLROAD · 2.7L
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Genuine OEM Used
SKU: 688323
Donor Vehicle: 2001 Audi ALLROAD · 2.7L
2 photos
$38.49
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Genuine OEM Used
SKU: 702416
Donor Vehicle: 2003 Volkswagen PASSAT · 2.8L
2 photos
$38.49
30-Day Returns
Genuine OEM Used
SKU: 461358
Donor Vehicle: 2005 Audi ALLROAD · 2.7L
2 photos
$38.49
30-Day Returns
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Audi 078121121K Thermostat Housing, a used OEM part from a donor vehicle. This genuine housing is designed for the 2.7L turbocharged and 2.8L naturally aspirated V6 engines found in the Audi A6, A6 Quattro, Allroad Quattro, and Volkswagen Passat. A failing thermostat housing often causes coolant leaks or engine overheating, as the plastic body can crack over time. This unit replaces the original cooling system component to restore proper engine temperature regulation.
Specifications
| Fits Vehicle Model | A6, Allroad, Passat |
| Fits Vehicle Make | Audi, Volkswagen |
| OEM Part No | 078-121-121-K (078121121K) |
| Category | Radiator / Coolant |
Compatible Vehicles
Fits 36 vehicle configurations across 2 makes, 1998-2005.
Check your specific vehicle before ordering.
This list shows year, make, and model. Some years have multiple trims or
engines that use different parts, and individual listings may have
additional fitment notes (e.g. “with sunroof only”). Review
the full variant list below, or
message us with your VIN
and we’ll confirm the match.
View all 36 vehicle configurations — 15 with fitment notes
| Year | Make | Model | Trim | Engine | Note |
|---|---|---|---|---|---|
| 1998 | Audi | A6 | Quattro Sedan | 2.8L V6 | |
| 2003 | Volkswagen | Passat | Wagon | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 1999 | Audi | A6 | Sedan | 2.8L V6 | |
| 2001 | Audi | A6 | Quattro Wagon | 2.8L V6 | For Vehicles Where Last 6 Digits of VIN Number are Greater Than 007001 |
| 2001 | Audi | A6 | Quattro Sedan | 2.8L V6 | For Vehicles Where Last 6 Digits of VIN Number are Greater Than 007001 |
| 2004 | Volkswagen | Passat | Sedan | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 2005 | Volkswagen | Passat | 4 Wagon | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 2004 | Volkswagen | Passat | 4 Wagon | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 2004 | Volkswagen | Passat | 4 Sedan | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 2002 | Volkswagen | Passat | 4 Sedan | 2.8L V6 | |
| 2001 | Audi | A6 | Sedan | 2.8L V6 | |
| 2001 | Audi | A6 | Quattro Sedan | 2.7L V6 Turbo | For Vehicles Where Last 6 Digits of VIN Number are Greater Than 007001 |
| 2001 | Volkswagen | Passat | 4 Wagon | 2.8L V6 | |
| 2003 | Volkswagen | Passat | 4 Wagon | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 2005 | Volkswagen | Passat | Sedan | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 2002 | Volkswagen | Passat | Wagon | 2.8L V6 | |
| 2002 | Volkswagen | Passat | Sedan | 2.8L V6 | |
| 2005 | Audi | Allroad | Quattro Wagon | 2.7L V6 Turbo | |
| 2002 | Volkswagen | Passat | 4 Wagon | 2.8L V6 | |
| 2002 | Audi | Allroad | Quattro Wagon | 2.7L V6 Turbo | |
| 2003 | Volkswagen | Passat | Sedan | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 2004 | Volkswagen | Passat | Wagon | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 1998 | Audi | A6 | Sedan | 2.8L V6 | |
| 2001 | Volkswagen | Passat | 4 Sedan | 2.8L V6 | |
| 2000 | Audi | A6 | Sedan | 2.8L V6 | |
| 2001 | Audi | Allroad | Quattro Wagon | 2.7L V6 Turbo | |
| 2001 | Volkswagen | Passat | Sedan | 2.8L V6 | |
| 2003 | Audi | A6 | Quattro Sedan | 2.7L V6 Turbo | |
| 2003 | Audi | Allroad | Quattro Wagon | 2.7L V6 Turbo | |
| 2002 | Audi | A6 | Quattro Sedan | 2.7L V6 Turbo | |
| 2004 | Audi | A6 | Quattro Sedan | 2.7L V6 Turbo | |
| 2005 | Volkswagen | Passat | 4 Sedan | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 2001 | Volkswagen | Passat | Wagon | 2.8L V6 | |
| 2005 | Volkswagen | Passat | Wagon | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |
| 2004 | Audi | Allroad | Quattro Wagon | 2.7L V6 Turbo | |
| 2003 | Volkswagen | Passat | 4 Sedan | 2.8L V6 | For Vehicles with Engine Code(s) ATQ |