2011-2026 Audi / Porsche Coolant / Heater Bypass Solenoid Valve 4H0121670A
OEM Part #: 4H0-121-670-A (4H0121670A)
Actual photo
The exact part you’ll receive — not a stock photo.
$18.99
Used
Donor2015 Audi A8 · 4.0L
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Genuine OEM Used
SKU: 674596
Donor Vehicle: 2015 Audi A8 · 4.0L
3 photos
$18.99
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Genuine OEM Used
SKU: 701427
Donor Vehicle: 2021 Audi SQ8 · 4.0L · 47k miles
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$19.99
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Genuine OEM Used
SKU: 692643
Donor Vehicle: 2017 Audi Q7 · 2.0L
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$20.49
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Genuine OEM Used
SKU: 665334
Donor Vehicle: 2015 Audi A8 · 4.0L
3 photos
$20.49
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An Audi Coolant / Heater Bypass Solenoid Valve, genuine OEM part 4H0121670A, now available as a used salvage component. This valve – also known as a coolant bypass or heater bypass solenoid valve – controls coolant flow to the heater core for cabin temperature regulation. It supersedes OEM numbers 4H0121670 and 4H0121671. Found in Audi A8, Q7, RS3, RS Q8, S8, SQ7, SQ8, TT, TTS, TT RS and Porsche Cayenne applications, it supports multiple turbocharged gas, diesel, and hybrid engine families including the 2.0L, 2.5L, 2.9L, 3.0L, and 4.0L. A failed valve can cause insufficient cabin heat or erratic temperature control.
Specifications
| Fits Vehicle Model | A8, Cayenne, Q7, RS Q8, RS3, S8, SQ7, SQ8, TT, TT RS, TTS |
| Fits Vehicle Make | Audi, Porsche |
| OEM Part No | 4H0-121-670-A (4H0121670A) |
| Compatible OEM Part No | 4H0-121-670, 4H0-121-671 |
| Category | Radiator / Coolant |
Compatible Vehicles
Fits 118 vehicle configurations across 2 makes, 2011-2026.
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 118 vehicle configurations — 39 with fitment notes
| Year | Make | Model | Trim | Engine | Note |
|---|---|---|---|---|---|
| 2026 | Audi | S8 | Sedan | 4.0L V8 Turbo | |
| 2025 | Audi | RS3 | Sedan | 2.5L l5 Turbo | |
| 2025 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | |
| 2023 | Audi | SQ8 | SUV | 4.0L V8 Turbo | |
| 2026 | Audi | RS3 | Sedan | 2.5L l5 Turbo | |
| 2026 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles with Production Date After 08/05/24 |
| 2025 | Audi | SQ8 | SUV | 4.0L V8 Turbo | |
| 2025 | Audi | S8 | Sedan | 4.0L V8 Turbo | |
| 2026 | Audi | SQ8 | SUV | 4.0L V8 Turbo | |
| 2024 | Audi | SQ8 | SUV | 4.0L V8 Turbo | |
| 2013 | Audi | TT | Quattro Coupe | 2.0L l4 Turbo | 2.5 LITER REAR |
| 2012 | Audi | TTS | Quattro Convertible | 2.0L l4 Turbo | 2.5 LITER REAR |
| 2012 | Audi | TTS | Quattro Coupe | 2.0L l4 Turbo | 2.5 LITER REAR |
| 2013 | Audi | TTS | Quattro Convertible | 2.0L l4 Turbo | 2.5 LITER REAR |
| 2013 | Audi | TTS | Quattro Coupe | 2.0L l4 Turbo | 2.5 LITER REAR |
| 2020 | Audi | SQ7 | SUV | 4.0L V8 Turbo | |
| 2020 | Audi | SQ8 | SUV | 4.0L V8 Turbo | |
| 2021 | Audi | SQ7 | SUV | 4.0L V8 Turbo | |
| 2021 | Audi | SQ8 | SUV | 4.0L V8 Turbo | |
| 2022 | Audi | SQ8 | SUV | 4.0L V8 Turbo | |
| 2022 | Audi | SQ7 | SUV | 4.0L V8 Turbo | |
| 2012 | Audi | TT | Quattro Convertible | 2.0L l4 Turbo | 2.5 LITER REAR |
| 2012 | Audi | TT | Quattro Coupe | 2.0L l4 Turbo | 2.5 LITER REAR |
| 2013 | Audi | TT | Quattro Convertible | 2.0L l4 Turbo | 2.5 LITER REAR |
| 2026 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 11/21/16 |
| 2025 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 11/21/16 |
| 2023 | Porsche | Cayenne | S Coupe SUV | 2.9L V6 Turbo | |
| 2022 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | Turbo GT Coupe 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 | Turbo S SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | GTS SUV | 4.0L V8 Turbo | |
| 2024 | Porsche | Cayenne | Turbo GT Coupe SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | Turbo Coupe SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | Turbo S SUV | 4.0L V8 Turbo | |
| 2024 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | GTS Coupe SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | GTS Coupe SUV | 4.0L V8 Turbo | |
| 2024 | Porsche | Cayenne | S Coupe SUV | 3.0L V6 Turbo | |
| 2024 | Porsche | Cayenne | S Coupe SUV | 4.0L V8 Turbo | |
| 2024 | Porsche | Cayenne | Coupe SUV | 3.0L V6 Turbo | |
| 2024 | Porsche | Cayenne | SUV | 3.0L V6 Turbo | |
| 2020 | Porsche | Cayenne | Turbo S Coupe SUV | 4.0L V8 Turbo | |
| 2020 | Porsche | Cayenne | Turbo S SUV | 4.0L V8 Turbo | |
| 2020 | Porsche | Cayenne | Turbo Coupe SUV | 4.0L V8 Turbo | |
| 2020 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2019 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | Turbo Coupe SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | Turbo Coupe SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | Turbo S Coupe SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | Turbo GT Coupe SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | S SUV | 2.9L V6 Turbo | |
| 2023 | Porsche | Cayenne | GTS SUV | 4.0L V8 Turbo | |
| 2021 | Porsche | Cayenne | Turbo S Coupe SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | Turbo S Coupe SUV | 4.0L V8 Turbo | |
| 2024 | Porsche | Cayenne | Turbo Coupe SUV | 4.0L V8 Turbo | |
| 2023 | Porsche | Cayenne | Turbo SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | GTS Coupe SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | GTS SUV | 4.0L V8 Turbo | |
| 2024 | Porsche | Cayenne | S SUV | 3.0L V6 Turbo | |
| 2024 | Porsche | Cayenne | S SUV | 4.0L V8 Turbo | |
| 2022 | Porsche | Cayenne | Turbo S SUV | 4.0L V8 Turbo | |
| 2022 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 11/21/16 |
| 2023 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 11/21/16 |
| 2021 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | |
| 2024 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 11/21/16 |
| 2024 | Audi | S8 | Sedan | 4.0L V8 Turbo | |
| 2023 | Audi | S8 | Sedan | 4.0L V8 Turbo | |
| 2022 | Audi | TT RS | Quattro Coupe | 2.5L l5 Turbo | |
| 2022 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles With Production date Up To 08/05/24 |
| 2024 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles With Production date Up To 08/05/24 |
| 2022 | Audi | S8 | Sedan | 4.0L V8 Turbo | |
| 2023 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles With Production date Up To 08/05/24 |
| 2021 | Audi | TT RS | Quattro Coupe | 2.5L l5 Turbo | |
| 2021 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles With Production date Up To 08/05/24 |
| 2023 | Audi | RS3 | Sedan | 2.5L l5 Turbo | |
| 2021 | Audi | S8 | Sedan | 4.0L V8 Turbo | |
| 2024 | Audi | RS3 | Sedan | 2.5L l5 Turbo | |
| 2020 | Audi | RS Q8 | SUV | 4.0L V8 Turbo | For Vehicles With Production date Up To 08/05/24 |
| 2021 | Audi | Q7 | SUV | 2.0L l4 Turbo | For Vehicles with Production Date After 11/21/16 |
| 2022 | Audi | RS3 | Sedan | 2.5L l5 Turbo | |
| 2018 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CTGA, CTGF |
| 2019 | Audi | Q7 | SUV | 2.0L l4 Turbo | |
| 2020 | Audi | TT RS | Quattro Coupe | 2.5L l5 Turbo | |
| 2019 | Audi | RS3 | Sedan | 2.5L l5 Turbo | |
| 2019 | Audi | TT RS | Quattro Coupe | 2.5L l5 Turbo | |
| 2016 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CTGA, CTGF |
| 2020 | Audi | Q7 | SUV | 2.0L l4 Turbo | |
| 2020 | Audi | RS3 | Sedan | 2.5L l5 Turbo | |
| 2017 | Audi | RS3 | Sedan | 2.5L l5 Turbo | |
| 2015 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CTGA, CTGF |
| 2015 | Audi | A8 | Quattro Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CTGA, CTGF |
| 2013 | Audi | A8 | Quattro Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CEUA |
| 2014 | Audi | A8 | Quattro Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CEUA |
| 2013 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CEUA |
| 2014 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CEUA |
| 2016 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CTGA, CTGF |
| 2014 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CEUA |
| 2013 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CEUA |
| 2012 | Audi | A8 | Quattro L Sedan | 4.2L V8 | For Vehicles with Engine Code(s) CDRA |
| 2012 | Audi | A8 | Quattro Sedan | 4.2L V8 | For Vehicles with Engine Code(s) CDRA |
| 2012 | Audi | TT RS | Quattro Coupe | 2.5L l5 Turbo | |
| 2011 | Audi | A8 | Quattro L Sedan | 4.2L V8 | For Vehicles with Engine Code(s) CDRA |
| 2011 | Audi | A8 | Quattro Sedan | 4.2L V8 | For Vehicles with Engine Code(s) CDRA |
| 2013 | Audi | TT RS | Quattro Coupe | 2.5L l5 Turbo | |
| 2015 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CTGA, CTGF |
| 2017 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CTGA, CTGF |
| 2018 | Audi | S8 | Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CTGA, CTGF |
| 2018 | Audi | RS3 | Sedan | 2.5L l5 Turbo | |
| 2018 | Audi | TT RS | Quattro Coupe | 2.5L l5 Turbo | |
| 2018 | Audi | Q7 | SUV | 2.0L l4 Turbo | |
| 2017 | Audi | Q7 | SUV | 2.0L l4 Turbo | |
| 2017 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | For Vehicles with Engine Code(s) CTGA, CTGF |
| 2020 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | |
| 2019 | Audi | A8 | Quattro L Sedan | 4.0L V8 Turbo | |
| 2020 | Audi | S8 | Sedan | 4.0L V8 Turbo |