The 06A 121 121C coolant flange is a Genuine Volkswagen Audi OEM thermostat housing cover for select Mk4 Golf, Jetta, Audi A4, and TT models equipped with the 1.8T or 2.0L engine. It restores a leak-free seal at the thermostat housing with a direct bolt-on fit and no modifications required.
$7.99
The 06A 121 121C is a Genuine Volkswagen Audi OEM thermostat housing cover. It fits select VW and Audi vehicles with the 1.8T and 2.0L four-cylinder engines. Mounted on the cylinder head, this flange seals the thermostat housing. As a result, it maintains proper coolant flow and system pressure throughout operation.
As a Genuine Volkswagen Audi part, the 06A 121 121C meets the exact factory specifications used in original vehicle assembly. Therefore, it delivers a precise bolt-on replacement with no modifications required. It also matches the original unit in fitment geometry, sealing surface accuracy, and material quality.
A cracking or failed thermostat housing cover produces symptoms that worsen over time. For this reason, you should not ignore the early warning signs.
Watch for the following:
Visible coolant seepage or drips near the thermostat housing
A persistent coolant odor from the engine bay after operation
A low coolant warning light with no obvious external source
In more advanced cases, a visual inspection will reveal a cracked or brittle housing. Furthermore, a leaking coolant flange causes progressive coolant loss and unstable engine temperatures. It can also lead to heater performance issues and, in severe cases, engine overheating.
OEM Reference: 06A 121 121C
Brand: Genuine Volkswagen Audi — factory OEM part
Thermostat housing cover — mounts on the cylinder head
OEM-matched construction for correct fit and sealing
Precision sealing surfaces to prevent coolant leaks
First, replace all associated O-rings and seals at the time of installation. This ensures a complete, leak-free repair. Next, inspect the thermostat for signs of wear or sticking while the housing is open. Additionally, torque all fasteners to factory specification to avoid cracking the housing sealing surface.
After installation, refill with the VW/Audi-approved coolant mixture. Finally, bleed the cooling system to remove trapped air before returning the vehicle to service.
This part does not fit 2002+ Golf or Jetta models with automatic transmission. It also does not fit any New Beetle applications.
Always verify fitment by VIN before ordering.
06A 121 121
06A 121 121A
06A 121 121B
| Weight | 0.35 lbs |
|---|---|
| Dimensions | 7.0 × 5.0 × 4.0 in |
| Year | Make | Model | Engine | Notes |
|---|---|---|---|---|
| 2000-2006 | Audi | TT | 1.8L | |
| 1998-2005 | Volkswagen | Beetle | 1.8L | |
| 1999-2005 | Volkswagen | Beetle | 1.9L | |
| 2006, 2010 | Volkswagen | Beetle | 2.0L | |
| 2006 | Volkswagen | GTI | 2.0L | |
| 1999-2006 | Volkswagen | Golf | 1.8L | |
| 2000-2006 | Volkswagen | Golf | 2.0L | |
| 1998-2005 | Volkswagen | Jetta | 1.8L | |
| 1998-2005, 2008-2011 | Volkswagen | Jetta | 2.0L |
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