Audi / Porsche Coolant Reservoir / Tank / Bottle Cap 4M0121321Q
OEM Part #: 4M0-121-321-Q (4M0121321Q)
Porsche Part #: PAB121321B
This page covers one exact OEM part number. Every unit we stocked has sold.
We may be able to get another
Used OEM parts are one-of-a-kind. We sometimes get another when we dismantle a matching vehicle, but we can’t say when — browse what’s in stock now:
Other Coolant Reservoir / Tank that may fit your vehicle
Coolant Reservoir / Bottle / Tank Cap
Coolant Reservoir / Bottle / Tank Cap
Coolant Reservoir / Bottle / Tank Cap
Coolant Reservoir / Tank / Bottle
Coolant Reservoir / Tank / Bottle
Coolant Reservoir / Tank / Bottle
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The OEM Coolant Reservoir Tank Cap (Part Number: 4M0121321Q) is crucial for maintaining optimal pressure within the coolant system of select Audi and Porsche models. Located atop the coolant reservoir, this cap ensures that the coolant remains contained and at proper levels, which is essential for effective engine cooling. It interfaces directly with the expansion tank, allowing for thermal expansion of the coolant during engine operation. Common issues requiring replacement include cracks or leaks in the cap, which can lead to coolant loss and engine overheating. This cap is compatible with various Audi models, including the Q5, Q7, and RS5, across model years 2016 to 2024, as well as the Porsche Cayenne from 2018 to 2024. Alternative terms include reservoir cap and radiator cap.
Specifications
| Fits Vehicle Model | A4, A5, A6, A8, Cayenne, Q5, Q5 PHEV, Q7, Q8, RS Q8, RS5, S4, S5, S6, S8, SQ5 |
| Fits Vehicle Make | Audi, Porsche |
| OEM Part No | 4M0-121-321-Q (4M0121321Q) |
| Porsche Part No | PAB121321B |
| Compatible OEM Part No | PAB12132100, 4M0-121-321-J, 4M0-121-321-K, 4M0-121-321-E, 4M0-121-321-H |
| Category | Radiator / Coolant |
Compatible Vehicles
Fits 183 vehicle configurations across 2 makes, 2017-2024.
View all 183 vehicle configurations — 113 with fitment notes
| Year | Make | Model | Trim | Engine | Note |
|---|---|---|---|---|---|
| 2017 | Audi | A4 | Sedan | 2.0L l4 Turbo | |
| 2017 | Audi | A4 | Quattro Sedan | 2.0L l4 Turbo | |
| 2017 | Audi | A5 | Quattro Convertible | 2.0L l4 Turbo | |
| 2017 | Audi | A5 | Quattro Coupe | 2.0L l4 Turbo | |
| 2017 | Audi | Q7 | SUV | 2.0L l4 Turbo | |
| 2018 | Audi | A4 | Sedan | 2.0L l4 Turbo | |
| 2018 | Audi | A4 | Quattro Sedan | 2.0L l4 Turbo | |
| 2018 | Audi | A5 | Quattro Convertible | 2.0L l4 Turbo | |
| 2018 | Audi | A5 | Quattro Coupe | 2.0L l4 Turbo | |
| 2018 | Audi | A5 | Hatchback | 2.0L l4 Turbo | |
| 2018 | Audi | Q7 | SUV | 2.0L l4 Turbo | |
| 2019 | Audi | A4 | Sedan | 2.0L l4 Turbo | |
| 2019 | Audi | A4 | Quattro Sedan | 2.0L l4 Turbo | |
| 2019 | Audi | A5 | Quattro Convertible | 2.0L l4 Turbo | |
| 2019 | Audi | A5 | Quattro Coupe | 2.0L l4 Turbo | |
| 2019 | Audi | A5 | Hatchback | 2.0L l4 Turbo | |
| 2019 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 11/04/19 |
| 2019 | Audi | Q7 | SUV | 3.0L V6 Supercharged | For Vehicles with Production Date After 11/04/19 |
| 2020 | Audi | A4 | Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2020 | Audi | A4 | Quattro Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2020 | Audi | A5 | Quattro Convertible | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2020 | Audi | A5 | Quattro Coupe | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2020 | Audi | A5 | Hatchback | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2020 | Audi | A6 | Quattro Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 07/06/20 |
| 2020 | Audi | Q5 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date Between 06/22/20 and 08/17/20 |
| 2020 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2020 | Audi | S4 | Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2020 | Audi | S5 | Convertible | 3.0L V6 Turbo | For Vehicles with Production Date After 05/25/20 |
| 2020 | Audi | S5 | Coupe | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2020 | Audi | S5 | Hatchback | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2020 | Audi | SQ5 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2021 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2021 | Audi | RS5 | Coupe | 2.9L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2021 | Audi | RS5 | Hatchback | 2.9L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2021 | Audi | S4 | Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2021 | Audi | S5 | Convertible | 3.0L V6 Turbo | For Vehicles with Production Date After 05/25/20 |
| 2021 | Audi | S5 | Coupe | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2021 | Audi | S5 | Hatchback | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2021 | Audi | SQ5 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2022 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2022 | Audi | RS5 | Coupe | 2.9L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2022 | Audi | RS5 | Hatchback | 2.9L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2022 | Audi | S4 | Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2022 | Audi | S5 | Convertible | 3.0L V6 Turbo | For Vehicles with Production Date After 05/25/20 |
| 2022 | Audi | S5 | Coupe | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2022 | Audi | S5 | Hatchback | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2022 | Audi | SQ5 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2019 | Porsche | Cayenne | SUV | 3.0L V6 Turbo | |
| 2019 | Porsche | Cayenne | S SUV | 2.9L V6 Turbo | |
| 2019 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2020 | Porsche | Cayenne | SUV | 3.0L V6 Turbo | |
| 2020 | Porsche | Cayenne | Coupe SUV | 3.0L V6 Turbo | |
| 2020 | Porsche | Cayenne | S Coupe SUV | 2.9L V6 Turbo | |
| 2020 | Porsche | Cayenne | S SUV | 2.9L V6 Turbo | |
| 2020 | Porsche | Cayenne | Turbo Coupe SUV | 4.0L V8 Turbo | |
| 2020 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | SUV | 3.0L V6 Turbo | |
| 2021 | Porsche | Cayenne | Coupe SUV | 3.0L V6 Turbo | |
| 2021 | Porsche | Cayenne | GTS Coupe SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | GTS SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | S Coupe SUV | 2.9L V6 Turbo | |
| 2021 | Porsche | Cayenne | S SUV | 2.9L V6 Turbo | |
| 2021 | Porsche | Cayenne | Turbo Coupe SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | SUV | 3.0L V6 Turbo | |
| 2022 | Porsche | Cayenne | Coupe SUV | 3.0L V6 Turbo | |
| 2022 | Porsche | Cayenne | GTS SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | S Coupe SUV | 2.9L V6 Turbo | |
| 2022 | Porsche | Cayenne | S SUV | 2.9L V6 Turbo | |
| 2022 | Porsche | Cayenne | Turbo Coupe SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | Turbo GT Coupe SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2019 | Audi | Q8 | SUV | 3.0L V6 Turbo | |
| 2020 | Audi | A6 | Quattro Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 09/07/20 |
| 2020 | Audi | A8 | Quattro L Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2020 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2020 | Audi | Q5 PHEV | SUV | 2.0L l4 Turbo | For Vehicles with Production Date Between 06/22/20 and 08/17/20 |
| 2020 | Audi | Q7 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2020 | Audi | Q8 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2020 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2020 | Audi | S6 | Sedan | 2.9L V6 Turbo | For Vehicles with Production Date After 09/07/20 |
| 2020 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2021 | Audi | A4 | Quattro Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2021 | Audi | A5 | Quattro Convertible | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2021 | Audi | A5 | Quattro Coupe | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2021 | Audi | A5 | Hatchback | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2021 | Audi | A6 | Quattro Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 07/06/20 |
| 2021 | Audi | A6 | Quattro Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 09/07/20 |
| 2021 | Audi | A8 | Quattro L Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2021 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2021 | Audi | Q5 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date Between 06/22/20 and 08/17/20 |
| 2021 | Audi | Q5 PHEV | SUV | 2.0L l4 Turbo | For Vehicles with Production Date Between 06/22/20 and 08/17/20 |
| 2021 | Audi | Q7 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2021 | Audi | Q8 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2021 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2021 | Audi | S6 | Sedan | 2.9L V6 Turbo | For Vehicles with Production Date After 09/07/20 |
| 2021 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2022 | Audi | A4 | Quattro Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2022 | Audi | A5 | Quattro Convertible | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2022 | Audi | A5 | Quattro Coupe | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2022 | Audi | A5 | Hatchback | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2022 | Audi | A6 | Quattro Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 07/06/20 |
| 2022 | Audi | A6 | Quattro Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 09/07/20 |
| 2022 | Audi | A8 | Quattro L Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2022 | Audi | Q5 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2022 | Audi | Q5 PHEV | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2022 | Audi | Q7 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2022 | Audi | Q8 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2022 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2022 | Audi | S6 | Sedan | 2.9L V6 Turbo | For Vehicles with Production Date After 09/07/20 |
| 2022 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2023 | Audi | A4 | Quattro Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2023 | Audi | A5 | Quattro Convertible | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2023 | Audi | A5 | Quattro Coupe | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2023 | Audi | A5 | Hatchback | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2023 | Audi | A6 | Quattro Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 07/06/20 |
| 2023 | Audi | A6 | Quattro Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 09/07/20 |
| 2023 | Audi | A8 | Quattro L Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2023 | Audi | Q5 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2023 | Audi | Q5 PHEV | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2023 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2023 | Audi | Q7 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2023 | Audi | Q8 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2023 | Audi | RS5 | Coupe | 2.9L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2023 | Audi | RS5 | Hatchback | 2.9L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2023 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2023 | Audi | S4 | Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2023 | Audi | S5 | Convertible | 3.0L V6 Turbo | For Vehicles with Production Date After 05/25/20 |
| 2023 | Audi | S5 | Coupe | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2023 | Audi | S5 | Hatchback | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2023 | Audi | S6 | Sedan | 2.9L V6 Turbo | For Vehicles with Production Date After 09/07/20 |
| 2023 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2023 | Audi | SQ5 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2018 | Porsche | Cayenne | S SUV | 3.0L V6 Supercharged | |
| 2020 | Porsche | Cayenne | Turbo S Coupe SUV | 4.0L V8 Turbo | |
| 2020 | Porsche | Cayenne | Turbo S SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | Turbo S Coupe SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | Turbo S SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | GTS Coupe SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | Turbo S Coupe SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | Turbo S SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | SUV | 3.0L V6 Turbo | |
| 2023 | Porsche | Cayenne | Coupe SUV | 3.0L V6 Turbo | |
| 2023 | Porsche | Cayenne | GTS Coupe SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | GTS SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | S Coupe SUV | 2.9L V6 Turbo | |
| 2023 | Porsche | Cayenne | S SUV | 2.9L V6 Turbo | |
| 2023 | Porsche | Cayenne | Turbo Coupe SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | Turbo GT Coupe SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | Turbo S Coupe SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | Turbo S SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2024 | Audi | A4 | Quattro Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2024 | Audi | A5 | Quattro Convertible | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2024 | Audi | A5 | Quattro Coupe | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2024 | Audi | A5 | Hatchback | 2.0L l4 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2024 | Audi | A6 | Quattro Sedan | 2.0L l4 Turbo | For Vehicles with Production Date After 07/06/20 |
| 2024 | Audi | A6 | Quattro Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 09/07/20 |
| 2024 | Audi | A8 | Quattro L Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2024 | Audi | Q5 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2024 | Audi | Q5 PHEV | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2024 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2024 | Audi | Q7 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2024 | Audi | Q8 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2024 | Audi | RS5 | Coupe | 2.9L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2024 | Audi | RS5 | Hatchback | 2.9L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2024 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles with Production Date After 08/24/20 |
| 2024 | Audi | S4 | Sedan | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2024 | Audi | S5 | Convertible | 3.0L V6 Turbo | For Vehicles with Production Date After 05/25/20 |
| 2024 | Audi | S5 | Coupe | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2024 | Audi | S5 | Hatchback | 3.0L V6 Turbo | For Vehicles with Production Date After 06/15/20 |
| 2024 | Audi | S6 | Sedan | 2.9L V6 Turbo | For Vehicles with Production Date After 09/07/20 |
| 2024 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Production Date After 06/08/20 |
| 2024 | Audi | SQ5 | SUV | 3.0L V6 Turbo | For Vehicles with Production Date After 06/22/20 |
| 2024 | Porsche | Cayenne | SUV | 3.0L V6 Turbo | |
| 2024 | Porsche | Cayenne | Coupe SUV | 3.0L V6 Turbo | |
| 2024 | Porsche | Cayenne | S Coupe SUV | 4.0L V8 Turbo | |
| 2024 | Porsche | Cayenne | S Coupe SUV | 3.0L V6 Turbo | |
| 2024 | Porsche | Cayenne | S SUV | 3.0L V6 Turbo | |
| 2024 | Porsche | Cayenne | S SUV | 4.0L V8 Turbo | |
| 2024 | Porsche | Cayenne | Turbo Coupe SUV | 4.0L V8 Turbo | |
| 2024 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2024 | Porsche | Cayenne | Turbo GT Coupe SUV | 4.0L V8 Turbo |