The 2021 Audi S4 has 19 electrical switch & relay parts with verified fitment on this page — 8 part types and 12 brands, covering both the 3.0L V6 Supercharged and the 3.0L V6 Turbocharged. Each part includes a manufacturer part number and application notes.
On the 2021 Audi S4, the switch and relay system covers the switches, relays and flashers that route power to everything the driver touches. 13 parts of the 19 listed are Oil Pressure Sender / Switch (9 parts), A/C Refrigerant Pressure Switch (2 parts) and Brake Light Switch (2 parts). The other 5 part types cover the remaining 6 parts.
The 2021 Audi S4 was sold with both the 3.0L V6 Supercharged and the 3.0L V6 Turbocharged. 15 parts fit every engine; the other 4 are engine-specific. Each part shows which engine(s) it fits.
12 brands supply electrical switch & relay parts for the 2021 Audi S4, led by VEMO (5 parts), WELLS (4 parts) and FOUR SEASONS (1 part), plus 9 more brands. Quality grades include Standard Replacement and Economy.
A "Popular" badge means the source catalog flagged the part as frequently chosen for the 2021 Audi S4. 1 part has it: HELLA 003259971 (Oil Pressure Sender / Switch). Each part number opens a page with every vehicle that part fits.
A/C Refrigerant Pressure Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| FOUR SEASONS Fits: all 2021 S4 engines | 37427 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Pressure Switch | View on Amazon |
| UAC Fits: all 2021 S4 engines | SW11224C | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Pressure Transducer | View on Amazon |
This table covers the pressure switches on the A/C circuit. Typical signs include a function that works intermittently, or a click without the accessory coming on. Inspect the connector behind the switch; heat-damaged terminals will kill the new part too.
2 A/C Refrigerant Pressure Switch parts are listed for the 2021 Audi S4, from FOUR SEASONS and UAC. All of them fit every engine offered in the 2021 S4.
Listed part numbers: FOUR SEASONS 37427 and UAC SW11224C.
Brake Light Switch
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| ÜRO PARTS Fits: all 2021 S4 engines | 5G0698459 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| WELLS Fits: all 2021 S4 engines | 1S10862 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon |
This table covers the pedal-mounted switch that turns on the brake lamps. Typical signs include a function that works intermittently, or a click without the accessory coming on. Inspect the connector behind the switch; heat-damaged terminals will kill the new part too.
2 Brake Light Switch parts are listed for the 2021 Audi S4, from ÜRO PARTS and WELLS. All of them fit every engine offered in the 2021 S4.
In the Economy grade, ÜRO PARTS supplies 1 part: the catalog's value-priced group. A representative part number is ÜRO PARTS 5G0698459.
The Standard Replacement section lists 1 option from WELLS — built to original-equipment specification. WELLS 1S10862 is listed in this group.
Part numbers include ÜRO PARTS 5G0698459 and WELLS 1S10862.
Horn Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| WELLS Fits: all 2021 S4 engines | 1R2303 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Mounting Hardware Included: No | View on Amazon |
This table covers the relays that control the Horn circuit. Typical signs include a click with no action, or a circuit that works only when you swap in a known-good relay. Swap with an identical relay in the fuse box before buying — it is the fastest test there is.
This group shows a single part: WELLS 1R2303.
Multi-Function Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| BOSCH Fits: all 2021 S4 engines | 0986332209 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Multi-Purpose Relay | View on Amazon |
| WELLS Fits: all 2021 S4 engines | 1R1007 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Mounting Hardware Included: No | View on Amazon |
This table covers the relays that control the Multi-Function circuit. Typical signs include a click with no action, or a circuit that works only when you swap in a known-good relay. Swap with an identical relay in the fuse box before buying — it is the fastest test there is.
2 Multi-Function Relay parts are listed for the 2021 Audi S4, from BOSCH and WELLS. All of them fit every engine offered in the 2021 S4.
Part numbers include BOSCH 0986332209 and WELLS 1R1007.
Oil Pressure Sender / Switch
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| WALKER PRODUCTS Fits: all 2021 S4 engines | 2561150 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HELLA Popular Fits: 3.0L V6 Turbocharged | 003259971 | 🇺🇸 US | 1-Pin ConnectorColor: Black or Turquoise | View on Amazon |
| FACET Fits: all 2021 S4 engines | 250053 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon | |
| ROSTRA Fits: 3.0L V6 Turbocharged | 501543 | 🇺🇸 US | View on Amazon | |
| STANDARD MOTOR PRODUCTS Fits: all 2021 S4 engines | PS778 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Connector Type: Plug InFinish: Metal, Plastic | View on Amazon |
| VEMO Fits: all 2021 S4 engines | V10720420 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Fits To 07/31/2023 | View on Amazon |
| WELLS Fits: all 2021 S4 engines | 1S12102 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon |
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GPD Fits: all 2021 S4 engines | 1816565 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon | |
| VEMO Fits: 3.0L V6 Turbocharged | V10730311 | 🇺🇸 US | 3 PINS | View on Amazon |
This table covers the senders and switches that report oil pressure to the gauge or lamp. Typical signs include a lamp that stays on, or a gauge that never moves. Confirm power and ground at the connector before replacing the sender or switch.
9 Oil Pressure Sender / Switch parts are listed for the 2021 Audi S4, from VEMO, WALKER PRODUCTS, HELLA and 5 other brands. HELLA 003259971 carries the "Popular" badge. 6 parts fit every engine; the other 3 are engine-specific.
Economy: 1 part, from WALKER PRODUCTS. A representative part number is WALKER PRODUCTS 2561150.
The Standard Replacement section: 6 options from HELLA, FACET, ROSTRA and 3 other brands. HELLA 003259971 is listed in this group.
2 ungrouped parts are not assigned to a grade, with the same engine-level match.
Listed part numbers: HELLA 003259971, WALKER PRODUCTS 2561150 and FACET 250053, plus the other parts above.
Power Window Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| VEMO Fits: 3.0L V6 Turbocharged | V10730721 | 🇺🇸 US | Front LeftSwitch Panel Assembly | View on Amazon |
This table covers the switches that command each window motor. Typical signs include a function that works intermittently, or a click without the accessory coming on. Inspect the connector behind the switch; heat-damaged terminals will kill the new part too.
One part is listed for the 2021 Audi S4 — VEMO V10730721.
Trunk Lid / Tailgate Release Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| VEMO Fits: all 2021 S4 engines | V10730458 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon |
This table covers the Trunk Lid / Tailgate Release switches. Typical signs include a function that works intermittently, or a click without the accessory coming on. Inspect the connector behind the switch; heat-damaged terminals will kill the new part too.
This group shows a single part: VEMO V10730458.
Turn Signal Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| VEMO Fits: all 2021 S4 engines | V10800003 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon |
This table covers the combination / turn-signal switches. Typical signs include a function that works intermittently, or a click without the accessory coming on. Inspect the connector behind the switch; heat-damaged terminals will kill the new part too.
One part is listed for the 2021 Audi S4 — VEMO V10800003.
Buying Electrical Switch & Relay Parts for a 2021 Audi S4
On this vehicle, the switch and relay system covers the switches, relays and flashers that route power to everything the driver touches.
- Match the engine first. Some electrical switch & relay parts fit every engine; others are engine-specific. Each row shows which engine(s) it fits.
- Read the notes on each row for position, trim and spec qualifiers before you order.
- Where labor overlaps, inspect the connector terminals behind any failed switch — heat damage there will kill the new part too.
- Cross-reference the manufacturer part number against your old part or a service-manual listing.
Start with the largest groups on this page: Oil Pressure Sender / Switch and A/C Refrigerant Pressure Switch .
Frequently Asked Questions
How many electrical switch & relay parts fit the 2021 Audi S4?
Our catalog currently lists 19 electrical switch & relay parts for the 2021 Audi S4 across 8 subcategories and 12 brands, covering both the 3.0L V6 Supercharged and the 3.0L V6 Turbocharged. Each part is matched to the engine(s) it fits.
Do electrical switch & relay parts differ between 2021 Audi S4 engines?
Some do. 15 parts fit every engine; the other 4 are engine-specific. Each row (and the filter at the top) shows which. If you're unsure which engine you have, check the emissions label under the hood or the 8th character of your VIN.
What are the signs of electrical switch & relay problems on a 2021 Audi S4?
Common symptoms include accessories that work intermittently, a click without action, or one function dead while its fuse tests fine. If you notice any of these, identify the affected subcategory above and cross-reference the part numbers listed.
What should I replace at the same time?
Where labor overlaps, inspect the connector terminals behind any failed switch — heat damage there will kill the new part too.
What do the market flags (US, CA, MX) on each part mean?
They show the market for which the manufacturer published application data for that part — where the vehicle was first sold, not where the part was made. If your 2021 Audi S4 was originally sold in the US, the safest choice is a part marked for the US market.
How do I make sure a part fits my 2021 Audi S4?
First match the engine — each row shows which engine(s) the part fits. Then swap a suspect relay with an identical known-good one from the fuse box before buying — it is the fastest diagnostic there is. The notes column carries position and trim qualifiers where they apply.
Other Parts for the 2021 Audi S4
Electrical Switch & Relay Parts for Other Audi S4 Years
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Manufacturer names, model designations and part numbers are used for identification and fitment reference only. AutoFactsDB is an independent catalog and is not affiliated with, endorsed by, or sponsored by any vehicle manufacturer displayed on this page.