7 Electrical switch & relay parts are listed for the 2021 BMW M440I, in 5 part types, covering the 3.0L L6 Turbocharged engine. Each one has a brand, a manufacturer part number and notes that say where it fits.
On the 2021 BMW M440I, the switch and relay system covers the switches, relays and flashers that route power to everything the driver touches. Most of the listed parts are A/C Refrigerant Pressure Switch (2 parts), Oil Pressure Sender / Switch (2 parts) and Brake Light Switch (1 part). The other 2 part types cover the remaining 2 parts.
The 2021 BMW M440I came with a single engine, the 3.0L L6 Turbocharged, and every part is verified against it.
5 brands supply electrical switch & relay parts for the 2021 BMW M440I, led by WELLS (3 parts), REIN (1 part) and UAC (1 part), plus 2 more brands.
Each part number listed for the 2021 BMW M440I opens a page with every vehicle that part fits.
A/C Refrigerant Pressure Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| REIN | ACS0243P | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | View on Amazon | |
| UAC | SW11170C | 🇺🇸 US 🇨🇦 CA | 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 BMW M440I, from REIN and UAC.
Listed part numbers: REIN ACS0243P and UAC SW11170C.
Brake Light Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| WELLS | 1S12667 | 🇺🇸 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.
One part is listed for the 2021 BMW M440I — WELLS 1S12667.
Horn Relay
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| VEMO | V20710021 | 🇺🇸 US 🇨🇦 CA | M440i 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.
This group shows a single part: VEMO V20710021.
Oil Pressure Sender / Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| GPD | 1816559 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | with Light | View on Amazon |
| WELLS | 1S16103 | 🇺🇸 US 🇨🇦 CA 🇲🇽 MX | 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.
2 Oil Pressure Sender / Switch parts are listed for the 2021 BMW M440I, from GPD and WELLS.
This group includes GPD 1816559 and WELLS 1S16103.
Turn Signal Switch
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| WELLS | 1S17939 | 🇺🇸 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 BMW M440I — WELLS 1S17939.
Buying Electrical Switch & Relay Parts for a 2021 BMW M440I
On this vehicle, the switch and relay system covers the switches, relays and flashers that route power to everything the driver touches.
- Confirm you have the 3.0L L6 Turbocharged engine — every part on this page is matched to it.
- 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: A/C Refrigerant Pressure Switch and Oil Pressure Sender / Switch .
Frequently Asked Questions
How many electrical switch & relay parts fit the 2021 BMW M440I?
Our catalog currently lists 7 electrical switch & relay parts for the 2021 BMW M440I across 5 subcategories and 5 brands, covering the 3.0L L6 Turbocharged engine. Each part is matched to the engine(s) it fits.
What are the signs of electrical switch & relay problems on a 2021 BMW M440I?
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 BMW M440I 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 BMW M440I?
Every part on this page is matched to the 3.0L L6 Turbocharged engine. 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 BMW M440I
Electrical Switch & Relay Parts for Other BMW M440I Years
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