Genuine Audi Coolant Reservoir Cap

Coolant Overflow Reservoir Cap

Select Vehicle by Model
Select Vehicle by VIN

Select Vehicle by Model

Model

Select Vehicle by VIN

For the most accurate results, select vehicle by your VIN (Vehicle Identification Number).

15 Coolant Reservoir Caps found

View related parts
Audi Reservoir Cap Part Number: 3B0-121-321
$23.24 MSRP: $37.18
You Save: $13.94 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cover; Cap, Radiator Cap
Fits the following Audi Models:
- A3 | 2006-2013 | Base, TDI | 4 Cyl 2.0 L DIESEL, 4 Cyl 2.0 L GAS
- A3 Quattro | 2006-2013 | Base | 4 Cyl 2.0 L GAS, 6 Cyl 3.2 L GAS
- A3 Sportback e-tron | 2016-2017 | Premium, Premium Plus, Prestige | 4 Cyl 1.4 L PLUG-IN HYBRID EV-GAS (PHEV)
- A4 | 2005-2016, 1998-2001 | Avant, Base, Cabriolet, Premium, Premium Plus, Prestige | 4 Cyl 1.8 L GAS, 4 Cyl 2.0 L GAS, 6 Cyl 2.8 L GAS, 6 Cyl 3.2 L GAS
- A4 Quattro | 2005-2016, 1998-2001 | Avant, Base, Cabriolet, Premium, Premium Plus, Prestige | 4 Cyl 1.8 L GAS, 4 Cyl 2.0 L FLEX, 4 Cyl 2.0 L GAS, 6 Cyl 2.8 L GAS, 6 Cyl 3.2 L GAS
- A5 | 2010-2014 | Cabriolet | 4 Cyl 2.0 L GAS
- A5 Quattro | 2008-2017 | Base, Cabriolet, Premium, Premium Plus, Prestige, Sport | 4 Cyl 2.0 L FLEX, 4 Cyl 2.0 L GAS, 6 Cyl 3.2 L GAS
- A6 | 2012-2018, 1998-2001 | Base, Premium, Premium Plus, Sport | 4 Cyl 2.0 L GAS, 6 Cyl 2.8 L GAS
- A6 Quattro | 2012-2018, 1998-2004 | Avant, Base, Competition, Premium, Premium Plus, Prestige, Sport, TDI Premium Plus, TDI Prestige | 4 Cyl 2.0 L GAS, 6 Cyl 2.8 L GAS, 6 Cyl 3.0 L DIESEL, 6 Cyl 3.0 L GAS, 8 Cyl 4.2 L GAS
- A7 Quattro | 2012-2018 | Base, Competition, Premium Plus, Prestige, TDI Premium Plus, TDI Prestige | 6 Cyl 3.0 L DIESEL, 6 Cyl 3.0 L GAS
View More
View related parts
Audi Reservoir Cap Part Number: 4M0-121-321-Q
$43.55 MSRP: $59.98
You Save: $16.43 (28%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cap
- Replaces: 4M0-121-321-H, 4M0-121-321-J, 4M0-121-321-K
Fits the following Audi Models:
- A4 | 2017-2020 | Premium, Premium Plus, Prestige, Titanium | 4 Cyl 2.0 L GAS
- A4 allroad | 2017-2020 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L GAS
- A4 Quattro | 2017-2021 | Premium, Premium Plus, Prestige, Ultra sport | 4 Cyl 2.0 L GAS, 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- A5 Quattro | 2018-2024 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L GAS, 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- A5 Sportback | 2018-2024 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L GAS, 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- A6 allroad | 2020-2025 | Premium Plus, Prestige | 6 Cyl 3.0 L MILD HYBRID EV-GAS (MHEV)
- A6 Quattro | 2019-2025 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L GAS, 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV), 6 Cyl 3.0 L MILD HYBRID EV-GAS (MHEV)
- A7 Sportback | 2019-2025 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L PLUG-IN HYBRID EV-GAS (PHEV), 6 Cyl 3.0 L MILD HYBRID EV-GAS (MHEV)
- A8 Quattro | 2019-2025 | L, L Plug-In Hybrid | 6 Cyl 3.0 L MILD HYBRID EV-GAS (MHEV), 6 Cyl 3.0 L PLUG-IN HYBRID EV-GAS (PHEV), 8 Cyl 4.0 L MILD HYBRID EV-GAS (MHEV)
- Q5 | 2018-2025 | Premium, Premium Plus, Prestige, Titanium Premium, Titanium Premium Plus, Titanium Prestige | 4 Cyl 2.0 L GAS, 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
View More
View related parts
Audi Auxiliary Radiator Cap Part Number: 4D0-133-335
$21.49 MSRP: $34.38
You Save: $12.89 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cap; Lower Mount Cap, Radiator Cap, Radiator Coupling
Fits the following Audi Models:
- A6 allroad | 2020-2025 | Premium Plus, Prestige | 6 Cyl 3.0 L MILD HYBRID EV-GAS (MHEV)
- A6 Quattro | 2019-2025 | Premium, Premium Plus, Prestige | 6 Cyl 3.0 L MILD HYBRID EV-GAS (MHEV)
- A7 Sportback | 2019-2025 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L PLUG-IN HYBRID EV-GAS (PHEV), 6 Cyl 3.0 L MILD HYBRID EV-GAS (MHEV)
- A8 Quattro | 2019-2025, 2013-2016 | Base, L, L Plug-In Hybrid, L TDI | 6 Cyl 3.0 L DIESEL, 6 Cyl 3.0 L GAS, 6 Cyl 3.0 L MILD HYBRID EV-GAS (MHEV), 6 Cyl 3.0 L PLUG-IN HYBRID EV-GAS (PHEV), 8 Cyl 4.0 L MILD HYBRID EV-GAS (MHEV)
- Q5 | 2021-2025 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- Q5 PHEV | 2020-2025 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L PLUG-IN HYBRID EV-GAS (PHEV)
- Q5 Sportback | 2021-2025 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- Q7 | 2020-2025 | Premium, Premium Plus, Prestige | 6 Cyl 3.0 L MILD HYBRID EV-GAS (MHEV)
- Q8 | 2019-2025 | Premium, Premium Plus, Prestige | 6 Cyl 3.0 L MILD HYBRID EV-GAS (MHEV)
- RS Q8 | 2020-2025 | Base | 8 Cyl 4.0 L MILD HYBRID EV-GAS (MHEV)
View More
View related parts
Audi Reservoir Cap Part Number: 2Q0-121-321-A
$26.86 MSRP: $42.98
You Save: $16.12 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cover; Cap
- Replaces: 3C0-121-321, 2Q0-121-321
Fits the following Audi Models:
- A3 | 2022-2024, 2017-2020 | Premium, Premium Plus, Prestige, Titanium | 4 Cyl 2.0 L GAS, 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- A3 Quattro | 2022-2025, 2015-2020 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L GAS, 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- A3 Sportback e-tron | 2017-2018 | Premium, Premium Plus, Prestige | 4 Cyl 1.4 L PLUG-IN HYBRID EV-GAS (PHEV)
- A7 Sportback | 2021-2022 | Premium Plus, Prestige | 4 Cyl 2.0 L PLUG-IN HYBRID EV-GAS (PHEV)
- A8 Quattro | 2020-2021 | L Plug-In Hybrid | 6 Cyl 3.0 L PLUG-IN HYBRID EV-GAS (PHEV)
- Q3 | 2018-2025 | Premium, Premium Plus, Prestige, S-Line Premium, S-Line Premium Plus, S-Line Prestige | 4 Cyl 2.0 L GAS
- Q3 Quattro | 2018 | Premium, Premium Plus | 4 Cyl 2.0 L GAS
- Q4 e-tron | 2022-2025 | Premium, Premium Plus, Prestige | BATTERY EV (EV/BEV)
- Q4 e-tron Sportback | 2022-2025 | Premium, Premium Plus, Prestige | BATTERY EV (EV/BEV)
- Q5 | 2021-2025 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
View More
View related parts
Audi Reservoir Cap Part Number: 8E0-121-321
$34.86 MSRP: $55.78
You Save: $20.92 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cover; Cap
Fits the following Audi Models:
- A4 | 2002-2006 | Base, Cabriolet | 4 Cyl 1.8 L GAS, 6 Cyl 3.0 L GAS
- A4 Quattro | 2002-2006 | Avant, Base, Cabriolet | 4 Cyl 1.8 L GAS, 6 Cyl 3.0 L GAS
- A6 | 2006-2011, 2002-2004 | Base | 6 Cyl 3.0 L GAS, 6 Cyl 3.2 L GAS
- A6 Quattro | 2000-2011 | Avant, Base | 6 Cyl 2.7 L GAS, 6 Cyl 3.0 L GAS, 6 Cyl 3.2 L GAS, 8 Cyl 4.2 L GAS
- A8 Quattro | 2004-2010 | Base, L | 12 Cyl 6.0 L GAS, 8 Cyl 4.2 L GAS
- S4 | 2004-2006 | Avant, Base, Cabriolet | 8 Cyl 4.2 L GAS
- S6 | 2007-2011 | Base | 10 Cyl 5.2 L GAS
- S8 | 2007-2009 | Base | 10 Cyl 5.2 L GAS
View More
View related parts
Audi Reservoir Cap Part Number: 420-121-321
$233.24 MSRP: $326.66
You Save: $93.42 (29%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cover; Cap
Fits the following Audi Models:
- R8 | 2014-2015, 2008-2012 | Base, GT, GT Spyder, Plus, Spyder | 10 Cyl 5.2 L GAS, 8 Cyl 4.2 L GAS
View related parts
Audi Reservoir Cap Part Number: 4B3-121-321
$42.35 MSRP: $58.34
You Save: $15.99 (28%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cover; Cap
Fits the following Audi Models:
- R8 | 2014-2015 | Spyder | 10 Cyl 5.2 L GAS, 8 Cyl 4.2 L GAS
- RS5 | 2013-2015 | Base, Cabriolet | 8 Cyl 4.2 L GAS
View related parts
Audi Reservoir Cap Part Number: 4M0-121-321-R
$18.51 MSRP: $29.62
You Save: $11.11 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cap
Fits the following Audi Models:
- A4 | 2020 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L GAS
- A4 allroad | 2021-2025 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- A4 Quattro | 2020-2025 | Premium, Premium Plus, Prestige, Ultra sport | 4 Cyl 2.0 L GAS, 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- A5 Quattro | 2021-2024 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- A5 Sportback | 2021-2025 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- Q5 | 2021-2024 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
- Q5 Sportback | 2021-2024 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L MILD HYBRID EV-GAS (MHEV)
View More
View related parts
Audi Reservoir Cap Part Number: 8B3-121-321
$14.03 MSRP: $22.44
You Save: $8.41 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cap
- Replaces: 4KE-121-321-A
Fits the following Audi Models:
- e-tron Quattro | 2021-2023, 2019 | Chronos Edition, Premium, Premium Plus, Prestige | BATTERY EV (EV/BEV)
- e-tron S | 2022-2023 | Premium Plus, Prestige | BATTERY EV (EV/BEV)
- e-tron S Sportback | 2022-2023 | Premium Plus, Prestige | BATTERY EV (EV/BEV)
- e-tron Sportback | 2020-2023 | Premium, Premium Plus, Prestige | BATTERY EV (EV/BEV)
- Q6 e-tron | 2025 | Premium, Premium Plus, Prestige | BATTERY EV (EV/BEV)
- Q8 e-tron | 2024 | Launch Edition, Premium, Premium Plus, Prestige | BATTERY EV (EV/BEV)
- Q8 e-tron Sportback | 2024-2025 | Launch Edition, Premium, Premium Plus, Prestige | BATTERY EV (EV/BEV)
- SQ6 e-tron | 2025 | Premium, Premium Plus, Prestige | BATTERY EV (EV/BEV)
- SQ8 e-tron | 2024 | Premium Plus, Prestige | BATTERY EV (EV/BEV)
- SQ8 e-tron Sportback | 2024-2025 | Premium Plus, Prestige | BATTERY EV (EV/BEV)
View More
View related parts
Audi Reservoir Cap Part Number: 1J0-121-321-B
$24.74 MSRP: $39.59
You Save: $14.85 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cover
Fits the following Audi Models:
- Q7 | 2011-2015 | Premium, Premium Plus, Prestige, TDI Premium, TDI Premium Plus, TDI Prestige | 6 Cyl 3.0 L DIESEL, 6 Cyl 3.0 L GAS
View related parts
Audi Reservoir Cap Part Number: 5Q0-121-321
$36.25 MSRP: $58.00
You Save: $21.75 (38%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cover; Cap
Fits the following Audi Models:
- A3 | 2015-2018 | Premium, Premium Plus, Prestige, TDI Premium, TDI Premium Plus, TDI Prestige | 4 Cyl 1.8 L GAS, 4 Cyl 2.0 L DIESEL, 4 Cyl 2.0 L GAS
- A3 Quattro | 2015-2018 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L GAS
- A3 Sportback e-tron | 2016-2017 | Premium, Premium Plus, Prestige | 4 Cyl 1.4 L PLUG-IN HYBRID EV-GAS (PHEV)
- A8 Quattro | 2011-2018 | Base, L, L Sport, L TDI, L W12 | 12 Cyl 6.3 L GAS, 6 Cyl 3.0 L DIESEL, 6 Cyl 3.0 L GAS, 8 Cyl 4.0 L GAS, 8 Cyl 4.2 L GAS
- Q3 | 2015-2017 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L GAS
- Q3 Quattro | 2015-2017 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L GAS
- RS3 | 2017-2018 | Base | 5 Cyl 2.5 L GAS
- S3 | 2015-2017 | Premium Plus, Prestige | 4 Cyl 2.0 L GAS
- S8 | 2013-2018 | Base, Plus | 8 Cyl 4.0 L GAS
- TT | 2009 | Base | 4 Cyl 2.0 L GAS
View More
View related parts
Audi Reservoir Cap Part Number: 8R0-121-585
$2.46 MSRP: $3.84
You Save: $1.38 (36%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Grommet
Fits the following Audi Models:
- Q5 | 2009-2012 | Premium, Premium Plus, Prestige | 4 Cyl 2.0 L GAS, 6 Cyl 3.2 L GAS
View related parts
Audi Reservoir Cap Part Number: 1J0-121-422
$3.64 MSRP: $5.68
You Save: $2.04 (36%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cap
Fits the following Audi Models:
- TT | 2000-2006 | Base | 4 Cyl 1.8 L GAS
- TT Quattro | 2000-2006 | ALMS Edition, Base, Special Edition | 4 Cyl 1.8 L GAS, 6 Cyl 3.2 L GAS
View related parts
Audi Reservoir Cap Part Number: 9J1-121-321
$10.55 MSRP: $16.48
You Save: $5.93 (36%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cap
Fits the following Audi Models:
- e-tron GT | 2022-2024 | Premium Plus, Prestige | BATTERY EV (EV/BEV)
View related parts
Audi Reservoir Cap Part Number: 1C9-121-321
$40.28 MSRP: $55.48
You Save: $15.20 (28%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Cover
Fits the following Audi Models:
- Q7 | 2007-2012 | Base, Premium, Prestige, TDI, TDI Premium, TDI Premium Plus, TDI Prestige | 6 Cyl 3.0 L DIESEL, 6 Cyl 3.6 L GAS, 8 Cyl 4.2 L GAS

Audi Coolant Reservoir Cap

The Audi Coolant Reservoir Cap keeps the coolant sealed and pressed to prevent leaking and contaminating, which can overheat the engine. Audi has built up a reputation over the past hundred years and more. What started off with water-cooled engines led to the creation of the quattro system that clings to wet roads with confidence. Virtual Cockpit screens give drivers sharp information. Not to be outdone, matrix headlights help drivers see further into the night. Audi is also pushing the envelope with its e-tron electric models and has conducted several real-world autonomous tests. The brand is committed to safer, cleaner and smarter mobility. Audi owners love the sharp drive, solid German build quality and advanced technology of their cars. Because of this, they feel premium and sporty. The Coolant Reservoir Cap is an important part of the vehicle. It is essential for any gasoline, diesel or battery powertrain. The Coolant Reservoir Cap locks to the expansion tank and holds the correct pressure so antifreeze stays in while air stays out. This prevents rust and sludge from forming in passages and protects temperature balance during heavy acceleration, long highway cruises and cold morning starts. Crafted from robust metal or sturdy plastic, the plug creates an effective barrier against vibration, heat cycles and road muck, aligning with Audi engineering's overall reliability intentions. An accurate fit for your Coolant Reservoir Cap ensures a consistent flow of heat through your cabin, as well as stable gauges among other benefits. It also lessens the chance of toxic ethylene glycol being spilled out, which eases the mind of the driver knowing emissions are kept in check.

Stick with genuine OEM Coolant Reservoir Cap when you need quality that holds up. Audi crafts these parts to hit strict factory specs for every single unit. They also run each part through rigorous checks during production to maintain high quality. You can find exact Audi Coolant Reservoir Cap you need in our huge stock at AudiPartsGiant.com. You'll love our low, economical prices too. Every OEM part carries a real manufacturer's warranty, so you can buy with confidence. Returns aren't a headache here because our policy is simple. Plus, our speedy delivery gets orders out fast. Shop today and buy with total peace of mind.