23 Electrical switch & relay parts are listed for the 2021 Audi A4, in 13 part types, covering both the 2.0L L4 ELECTRIC/GAS Turbocharged and the 2.0L L4 Turbocharged. Each one has a brand, a manufacturer part number and notes that say where it fits.
The switch and relay system on the 2021 Audi A4 covers the switches, relays and flashers that route power to everything the driver touches. The largest groups are Oil Pressure Sender / Switch (7 parts), Multi-Function Relay (3 parts) and A/C Refrigerant Pressure Switch (2 parts). The other 10 part types cover the remaining 11 parts.
The 2021 Audi A4 was sold with both the 2.0L L4 ELECTRIC/GAS Turbocharged and the 2.0L L4 Turbocharged. Every part on this page is engine-specific. Each part shows which engine(s) it fits.
10 brands supply electrical switch & relay parts for the 2021 Audi A4, led by HELLA (6 parts), WELLS (5 parts) and VEMO (4 parts), plus 7 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 A4. 2 parts have it, including REIN ELP0078 (Oil Pressure Sender / Switch) and HELLA 009600281 (Oil Pressure Sender / Switch). Each part number opens a page with every vehicle that part fits.
A/C Condenser Fan Motor Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HELLA Fits: 2.0L L4 Turbocharged | 933332451 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 4-pin connector | View on Amazon |
This table covers the relays that control the A/C Condenser Fan Motor 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.
One part is listed for the 2021 Audi A4 — HELLA 933332451.
A/C Refrigerant Pressure Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| FOUR SEASONS Fits: 2.0L L4 Turbocharged | 37427 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Pressure Switch | View on Amazon |
| UAC Fits: 2.0L L4 Turbocharged | SW11103C | 🇺🇸 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 A4, from FOUR SEASONS and UAC.
Part numbers include FOUR SEASONS 37427 and UAC SW11103C.
Accessory Power Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HELLA Fits: 2.0L L4 Turbocharged | 933332451 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 4-pin connector | View on Amazon |
This table covers the relays that control the Accessory Power 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: HELLA 933332451.
Brake Light Switch
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| ÜRO PARTS Fits: 2.0L L4 Turbocharged | 5G0698459 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | A4 Quattro | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| WELLS Fits: 2.0L L4 Turbocharged | 1S10862 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | A4 Quattrowith 12 Volt System | 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 A4, from ÜRO PARTS and WELLS.
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.
Fog / Driving Lamp Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HELLA Fits: 2.0L L4 Turbocharged | 933332451 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 4-pin connector | View on Amazon |
This table covers the relays that control the Fog / Driving Lamp 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.
One part is listed for the 2021 Audi A4 — HELLA 933332451.
Fuel Pump / Circuit Opening Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HELLA Fits: 2.0L L4 Turbocharged | 933332451 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 4-pin connector | View on Amazon |
This table covers the relays that control the Fuel Pump / Circuit Opening 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.
One part is listed for the 2021 Audi A4 — HELLA 933332451.
Horn Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| WELLS Fits: 2.0L L4 Turbocharged | 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: 2.0L L4 Turbocharged | 0986332209 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Multi-Purpose Relay | View on Amazon |
| BOSCH Fits: 2.0L L4 Turbocharged | 0986AH0080 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Multi-Purpose Relay | View on Amazon |
| WELLS Fits: 2.0L L4 Turbocharged | 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.
3 Multi-Function Relay parts are listed for the 2021 Audi A4, from BOSCH and WELLS.
Listed part numbers: BOSCH 0986332209, BOSCH 0986AH0080 and WELLS 1R1007.
Oil Pressure Sender / Switch
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| REIN Popular Fits: 2.0L L4 Turbocharged | ELP0078 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | A4 QuattroBrown, with .55-.85 Bar | View on Amazon |
| WALKER PRODUCTS Fits: 2.0L L4 Turbocharged | 2561102 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | A4 Quattro | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HELLA Popular Fits: 2.0L L4 Turbocharged | 009600281 | 🇺🇸 US | 1-Pin ConnectorHousing Color: Green | View on Amazon |
| STANDARD MOTOR PRODUCTS Fits: 2.0L L4 Turbocharged | PS665 | 🇲🇽 MX | BlackColor: Green | View on Amazon |
| VEMO Fits: 2.0L L4 Turbocharged | V10720420 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Fits To 07/31/2023 | View on Amazon |
| WELLS Fits: 2.0L L4 Turbocharged | 1S16087 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | A4 Quattro0.3 - 0.6 Bar | View on Amazon |
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| WELLS Fits: 2.0L L4 Turbocharged | 1S17518 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | A4 Quattro0.55 - 0.85 Bar | 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.
7 Oil Pressure Sender / Switch parts are listed for the 2021 Audi A4, from WELLS, REIN, WALKER PRODUCTS and 3 other brands. REIN ELP0078 carries the "Popular" badge.
Economy: 2 parts, from REIN and WALKER PRODUCTS. A representative part number is REIN ELP0078.
The Standard Replacement section: 4 options from HELLA, STANDARD MOTOR PRODUCTS, VEMO and 1 other brand. HELLA 009600281 is listed in this group.
1 ungrouped part is not assigned to a grade, with the same engine-level match.
Part numbers include REIN ELP0078, WALKER PRODUCTS 2561102 and HELLA 009600281, among others listed above.
Power Window Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| VEMO Fits: 2.0L L4 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 A4 — VEMO V10730721.
Radiator Fan Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HELLA Fits: 2.0L L4 Turbocharged | 933332451 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 4-pin connector | View on Amazon |
This table covers the relays that control the Radiator Fan 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: HELLA 933332451.
Trunk Lid / Tailgate Release Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| VEMO Fits: 2.0L L4 Turbocharged | V10730458 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | A4 Quattro | 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: 2.0L L4 Turbocharged | V10800003 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | A4 Quattro | 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 A4 — VEMO V10800003.
Buying Electrical Switch & Relay Parts for a 2021 Audi A4
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. Every electrical switch & relay part here is 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 Multi-Function Relay .
Frequently Asked Questions
How many electrical switch & relay parts fit the 2021 Audi A4?
Our catalog currently lists 23 electrical switch & relay parts for the 2021 Audi A4 across 13 subcategories and 10 brands, covering both the 2.0L L4 ELECTRIC/GAS Turbocharged and the 2.0L L4 Turbocharged. Each part is matched to the engine(s) it fits.
Do electrical switch & relay parts differ between 2021 Audi A4 engines?
Yes. Every electrical switch & relay part on this page is engine-specific. Each row shows which engine(s) it fits — use the filter at the top to hide the rest. 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 A4?
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 A4 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 A4?
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 A4
Electrical Switch & Relay Parts for Other Audi A4 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.