The 2020 Mazda 3 has 27 electrical switch & relay parts with verified fitment on this page — 10 part types and 9 brands, covering both the 2.0L L4 and the 2.5L L4. Each part includes a manufacturer part number and application notes.
On the 2020 Mazda 3, the switch and relay system covers the switches, relays and flashers that route power to everything the driver touches. 15 parts of the 27 listed are Brake Light Switch (8 parts), Horn Relay (4 parts) and A/C Compressor Relay (3 parts). The other 7 part types cover the remaining 12 parts.
The 2020 Mazda 3 was sold with both the 2.0L L4 and the 2.5L L4. 11 parts fit every engine; the other 16 are engine-specific. Each part shows which engine(s) it fits.
The most listed brands for 2020 Mazda 3 electrical switch & relay parts are STANDARD MOTOR PRODUCTS (12 parts), WELLS (4 parts) and HOLSTEIN (3 parts), plus 6 more brands. Quality grades include Economy and Standard Replacement.
3 parts on this 2020 Mazda 3 page carry a "Popular" badge — the source catalog's flag for options frequently chosen for this vehicle — including STANDARD MOTOR PRODUCTS SLS355T (Brake Light Switch) and ULTRA-POWER SLS355 (Brake Light Switch). Click any part number to see every vehicle that part fits.
A/C Compressor Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HOLSTEIN Fits: 2.5L L4 | 2RSW0006 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 3 Base ModelControl Relay | View on Amazon |
| STANDARD MOTOR PRODUCTS Fits: 2.5L L4 | RY805T | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | T-Series | View on Amazon |
| STANDARD MOTOR PRODUCTS Fits: 2.5L L4 | RY805 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Functions: Multi-Function Relay | View on Amazon |
This table covers the relays that control the A/C Compressor 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 A/C Compressor Relay parts for the 2020 Mazda 3 come from 2 brands — STANDARD MOTOR PRODUCTS and HOLSTEIN.
Part numbers include HOLSTEIN 2RSW0006, STANDARD MOTOR PRODUCTS RY805T and STANDARD MOTOR PRODUCTS RY805.
A/C Refrigerant Pressure Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| UAC Fits: all 2020 3 engines | SW11649C | 🇺🇸 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.
This group shows a single part: UAC SW11649C.
A/C System Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| UAC Fits: 2.5L L4 | RE8414 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Fits Base ModelEngine VIN Lor i Grand Touringor 3 Base Model | View on Amazon |
| UAC Fits: 2.5L L4 | RE8415 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Fits 3 Base ModelGT Modelor I Sport or i Modelor Preferred or Select | View on Amazon |
This table covers the relays that control the A/C System 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 A/C System Relay parts for the 2020 Mazda 3 come from UAC.
Part numbers include UAC RE8414 and UAC RE8415.
Body Wiring Harness Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| STANDARD MOTOR PRODUCTS Fits: 2.5L L4 | RY805T | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | T-Series | View on Amazon |
| STANDARD MOTOR PRODUCTS Fits: 2.5L L4 | RY805 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Functions: Multi-Function Relay | View on Amazon |
This table covers the relays that control the Body Wiring Harness 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 Body Wiring Harness Relay parts for the 2020 Mazda 3 come from STANDARD MOTOR PRODUCTS.
Listed part numbers: STANDARD MOTOR PRODUCTS RY805T and STANDARD MOTOR PRODUCTS RY805.
Brake Light Switch
Economy
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| STANDARD MOTOR PRODUCTS Popular Fits: all 2020 3 engines | SLS355T | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | T-SeriesColor/Finish: Blue, Gray | View on Amazon |
| ULTRA-POWER Popular Fits: 2.5L L4 | SLS355 | 🇺🇸 US 🇨🇦 CA | 3 | View on Amazon |
| AUTOTECNICA Fits: all 2020 3 engines | MA1319181 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon | |
| DORMAN Fits: all 2020 3 engines | 920493 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 3 Base Model | View on Amazon |
Standard Replacement
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| STANDARD MOTOR PRODUCTS Popular Fits: all 2020 3 engines | SLS355 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Color/Finish: Black, Blue | View on Amazon |
| BECK/ARNLEY Fits: all 2020 3 engines | 2012742 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 3 Base Model | View on Amazon |
| ROSTRA Fits: all 2020 3 engines | 620296 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 3 Base Model | View on Amazon |
| WELLS Fits: all 2020 3 engines | 1S8007 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 3 Base Model | 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.
8 Brake Light Switch parts for the 2020 Mazda 3 come from 7 brands — STANDARD MOTOR PRODUCTS, ULTRA-POWER, AUTOTECNICA and 4 other brands. The "Popular" part is STANDARD MOTOR PRODUCTS SLS355T. 7 parts fit every engine; the other 1 is engine-specific.
The Economy section lists 4 options from STANDARD MOTOR PRODUCTS, ULTRA-POWER, AUTOTECNICA and 1 other brand — the catalog's value-priced group. STANDARD MOTOR PRODUCTS SLS355T is listed in this group.
In the Standard Replacement grade, STANDARD MOTOR PRODUCTS, BECK/ARNLEY, ROSTRA and 1 other brand supply 4 parts: built to original-equipment specification. A representative part number is STANDARD MOTOR PRODUCTS SLS355.
Part numbers include STANDARD MOTOR PRODUCTS SLS355T, ULTRA-POWER SLS355 and AUTOTECNICA MA1319181, among others listed above.
Fog / Driving Lamp Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HOLSTEIN Fits: 2.5L L4 | 2RSW0006 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 3 Base Model | View on Amazon |
| STANDARD MOTOR PRODUCTS Fits: 2.5L L4 | RY805T | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | T-Series | View on Amazon |
| STANDARD MOTOR PRODUCTS Fits: 2.5L L4 | RY805 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Functions: Multi-Function Relay | 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.
3 Fog / Driving Lamp Relay parts for the 2020 Mazda 3 come from 2 brands — STANDARD MOTOR PRODUCTS and HOLSTEIN.
Part numbers include HOLSTEIN 2RSW0006, STANDARD MOTOR PRODUCTS RY805T and STANDARD MOTOR PRODUCTS RY805.
Fuel Pump / Circuit Opening Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| STANDARD MOTOR PRODUCTS Fits: all 2020 3 engines | RY1963 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 3 Base ModelMain | 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.
This group shows a single part: STANDARD MOTOR PRODUCTS RY1963.
Horn Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HOLSTEIN Fits: 2.5L L4 | 2RSW0006 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 3 Base Model | View on Amazon |
| STANDARD MOTOR PRODUCTS Fits: 2.5L L4 | RY805T | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | T-Series | View on Amazon |
| STANDARD MOTOR PRODUCTS Fits: 2.5L L4 | RY805 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | Functions: Multi-Function Relay | View on Amazon |
| WELLS Fits: all 2020 3 engines | 1R2324 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 3 Base Model | 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.
4 Horn Relay parts are listed for the 2020 Mazda 3, from STANDARD MOTOR PRODUCTS, HOLSTEIN and WELLS. 1 part fits every engine; the other 3 are engine-specific.
This group includes HOLSTEIN 2RSW0006, STANDARD MOTOR PRODUCTS RY805T and STANDARD MOTOR PRODUCTS RY805 and the remaining parts above.
Ignition Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| STANDARD MOTOR PRODUCTS Fits: all 2020 3 engines | RY1963 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 3 Base Model | View on Amazon |
This table covers the relays that control the Ignition 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 2020 Mazda 3 — STANDARD MOTOR PRODUCTS RY1963.
Ignition Starter Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| WELLS Fits: 2.0L L4 | 1S17727 | 🇨🇦 CA | Fits 3 Base ModelSilver | View on Amazon |
| WELLS Fits: 2.0L L4 | 1S17728 | 🇨🇦 CA | Fits 3 Base Modelwith Bright Finish | View on Amazon |
This table covers the ignition switches that feed the starter 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.
WELLS supplies both parts for the 2020 Mazda 3.
Part numbers include WELLS 1S17727 and WELLS 1S17728.
Buying Electrical Switch & Relay Parts for a 2020 Mazda 3
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: Brake Light Switch and Horn Relay .
Frequently Asked Questions
How many electrical switch & relay parts fit the 2020 Mazda 3?
Our catalog currently lists 27 electrical switch & relay parts for the 2020 Mazda 3 across 10 subcategories and 9 brands, covering both the 2.0L L4 and the 2.5L L4. Each part is matched to the engine(s) it fits.
Do electrical switch & relay parts differ between 2020 Mazda 3 engines?
Some do. 11 parts fit every engine; the other 16 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 2020 Mazda 3?
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 2020 Mazda 3 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 2020 Mazda 3?
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 2020 Mazda 3
Electrical Switch & Relay Parts for Other Mazda 3 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.