BMW Electrical Sensors, Switches, & Relays for BMW 3 Series E46 (1999-2005)

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Electrical gremlins can be very frustrating. Luckily your BMW's electrical system is better than most, even if it's 25 years old. Here you will find electrical relays, sensors, switches, and modules for the engine, camshaft, and crankshaft. Our parts are OEM, Genuine BMW, or approved aftermarket brands that we have an excellent track record with. There is no middle ground with electrical parts - it either works perfectly or not. And there's nothing more frustrating than a new part that fails right out of the box. So it's important to choose quality replacement parts over a cheap but faulty piece.

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ECS Heavy Duty Ground Cable Upgrade (12421737755) - E30, E36, E39, E4...
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ECS - Corporate Logo
T#:49996974
Part#: 059235LA01
In Stock
Sale - Save 25% $ 29.99

This product was last offered at the strikethrough price on
11-07-2026

$ 22.49 USD
Free Shipping
Sale - Save 25%
$ 29.99

This product was last offered at the strikethrough price on
11-07-2026

$ 22.49 USD
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If you're experiencing hard starting, flaky charging, or other electrical issues, your engine ground strap may be the culprit. On older BMWs, the engine ground strap is a thin, non-insulated cable that spans from the engine mount arm to the frame horn. Despite the seemingly simple nature of this part, on older cars, it is known to cause massive headaches. Due to its non-insulated design, years of exposure to water, dirt, and road salt will cause the wire to corrode, ultimately leading to complete failure. A break in this cable will cause an open circuit, resulting in issues with the vehicle's electrical system and potentially leading to a no-start condition.

To solve this issue, ECS has engineered an exact-fit, upgraded ground strap for your BMW! Unlike its OEM counterpart, this design features insulated, large-gauge copper wire for dependable conductivity and long-lasting durability. Additionally, factory-style lugs are zinc-coated, crimped, and soldered, ensuring protection against corrosion and oxidation.

Whether you're replacing a visibly corroded strap or proactively preventing failure, this solution from ECS is sure to provide lasting performance and protection.

FEATURES

Direct-fit replacement and upgrade for E30 (318i/is), E36, E39, E46, and others Solves intermittent grounding issues caused by aging OEM straps Clean, stealthy design that fits seamlessly in factory engine bays Factory length and lug orientation for drop-in fitment 2 AWG tinned copper cable for excellent conductivity and corrosion resistance Zinc-coated lugs, crimped and soldered to resist moisture and oxidation Black UL1015-grade insulation withstands oil, heat, and abrasion Discreet ECS label for a clean, OEM+ look Replaces OEM part numbers 12421737755 and 12421714262.

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New Alternator - 120A
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Bavarian Autosport - Corporate Logo
T#:25042543
Part#: 12317501690
In Stock
Sale - Save 20% $ 211.99

This product was last offered at the strikethrough price on
11-07-2026

$ 169.59 USD
Free Shipping on orders $49 and up
Sale - Save 20%
$ 211.99

This product was last offered at the strikethrough price on
11-07-2026

$ 169.59 USD
Free Shipping on orders $49 and up
OEM Starter Motor - E46 M3 2001-2006
We Price Match - Give Us A Call or Chat!
Valeo - Corporate Logo
T#:2988
Part#: 12417835735
Ships in 1 Business Day
$ 389.99 USD
Free Shipping
$ 389.99 USD
Free Shipping
This is the starter motor for BMW E46 M3 2001-2006 is an OEM Valeo unit.

This item fits the following BMWs:
2001-2006 E46 BMW M3. M3 Convertible
2001-2002 Z3 BMW Z3 M Roadster Z3 M Coupe
2005-2008 E85 BMW Z4 M Roadster Z4 M Coupe
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Alternator - 120amp
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Bavarian Autosport - Corporate Logo
T#:25042542
Part#: 12317831436
In Stock
Sale - Save 25% $ 222.99

This product was last offered at the strikethrough price on
11-07-2026

$ 167.24 USD
Free Shipping on orders $49 and up
Sale - Save 25%
$ 222.99

This product was last offered at the strikethrough price on
11-07-2026

$ 167.24 USD
Free Shipping on orders $49 and up

E46 M3, MZ3 S54 OEM Valeo Alternator (New)
We Price Match - Give Us A Call or Chat!
Valeo - Corporate Logo
T#:377735
Part#: 12317831436
In Stock at Vendor
$ 522.00

This product was last offered at the strikethrough price on
07-16-2026

$ 473.99 USD
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$ 473.99 USD
Free Shipping

The alternator in your vehicle keeps the battery at full charge when your engine is running. Because all of your electronic systems run off of this small piece, it's important that it is operational. If your lights are dim while driving or your battery dies within minutes of starting your car, it's time for a new alternator.

This is a NEW alternator from the OEM manufacturer, Valeo. No core charge applies.

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Precision Raceworks - Corporate Logo
T#:35559424
Part#: 201-0411
In Stock
$ 34.99 USD
Free Shipping on orders $49 and up
n Ethanol Sensor Breakout Harness provides a clean wiring solution by splitting the signal from your ethanol content sensor between two analyzers, such as an ECU/controller and a gauge or Bluetooth display, without modifying your existing harness.his setup enables real-time ethanol level monitoring and facilitates comprehensive DME/ECU adjustments for enhanced automotive performance.citeturn0search0
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Hitachi - Corporate Logo
T#:48850072
Part#: 12147539165
In Stock
$ 41.99 USD
Free Shipping on orders $49 and up
$ 41.99 USD
Free Shipping on orders $49 and up
A bad cam sensor can cause a variety of problems from hard starting to stalling at low speeds. Cam sensor replacement has been known to cure many drivabilty issues. Uses O-ring # 12 141 748 398 (not included)
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Valeo - Corporate Logo
T#:371896
Part#: 12317501599
Ships on Dec 7, 2026
$ 323.99 USD
Free Shipping
$ 323.99 USD
Free Shipping

The alternator in your vehicle keeps the battery at full charge when your engine is running. Because all of your electronic systems run off of this small piece, it's important that it is operational. If your lights are dim while driving or your battery dies within minutes of starting your car, it's time for a new alternator.

This is a NEW alternator from the OEM manufacturer, Valeo. No core charge applies. Valeo is an OEM manufacturer for many BMW alternators - save money by buying the same alternator in a different box!

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LK-2M 2 Pin Connector Package
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ECS - Corporate Logo
T#:40072446
Part#: LK2M
In Stock
Sale - Save 34% $ 6.99

This product was last offered at the strikethrough price on
11-07-2026

$ 4.61 USD
Free Shipping on orders $49 and up
Sale - Save 34%
$ 6.99

This product was last offered at the strikethrough price on
11-07-2026

$ 4.61 USD
Free Shipping on orders $49 and up

Includes connector housing with terminals and seals. Commonly used for the engine oil pressure switch.

ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need.

Each connector includes an additional terminal in case one becomes lost or damaged during installation.

Suggested tools:

Suggested crimping pliers: T#387193
Wire De-pin tools:
12pc De-Pin Tool Set - T#386379
23pc De-Pin Tool Set - T#641943

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3 Pin Connector
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ECS - Corporate Logo
T#:33412931
Part#: 12527519996
In Stock
Sale - Save 40% $ 10.99

This product was last offered at the strikethrough price on
11-07-2026

$ 6.59 USD
Free Shipping on orders $49 and up
Sale - Save 40%
$ 10.99

This product was last offered at the strikethrough price on
11-07-2026

$ 6.59 USD
Free Shipping on orders $49 and up

Includes connector housing with terminals and seals. Commonly used for the pencil-style ignition coil connector.

ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need.

Each connector includes an additional terminal in case one becomes lost or damaged during installation.

*OEM cross reference PN# 12527519996 - Commonly used for the pencil-style ignition coil connector.

Please reference the original part number from the existing connector to confirm fitment, before ordering.

Suggested tools:

Suggested crimping pliers: T#387193
Wire De-pin tools:
12pc De-Pin Tool Set - T#386379
23pc De-Pin Tool Set - T#641943

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3 Pin Connector
10X Entries Into Our F80 M3 Sweepstakes 10X Entries For Our Spin To Win Sweepstakes!
ECS - Corporate Logo
T#:33412918
Part#: 12521732596
In Stock
Sale - Save 40% $ 10.99

This product was last offered at the strikethrough price on
11-07-2026

$ 6.59 USD
Free Shipping on orders $49 and up
Sale - Save 40%
$ 10.99

This product was last offered at the strikethrough price on
11-07-2026

$ 6.59 USD
Free Shipping on orders $49 and up

Includes connector housing with terminals and seals. Commonly used for the camshaft position sensor.

ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need.

Each connector includes an additional terminal in case one becomes lost or damaged during installation.

*OEM cross reference PN# 12521732596 - Commonly used for the camshaft position sensor.

Please reference the original part number from the existing connector to confirm fitment, before ordering.

Suggested tools:

Suggested crimping pliers: T#387193
Wire De-pin tools:
12pc De-Pin Tool Set - T#386379
23pc De-Pin Tool Set - T#641943

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3 Pin Connector
10X Entries Into Our F80 M3 Sweepstakes 10X Entries For Our Spin To Win Sweepstakes!
ECS - Corporate Logo
T#:33412947
Part#: 12521433916
In Stock
Sale - Save 40% $ 10.99

This product was last offered at the strikethrough price on
11-07-2026

$ 6.59 USD
Free Shipping on orders $49 and up
Sale - Save 40%
$ 10.99

This product was last offered at the strikethrough price on
11-07-2026

$ 6.59 USD
Free Shipping on orders $49 and up

Includes connector housing with terminals and seals. Commonly used for the crankshaft position sensor.

ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need.

Each connector includes an additional terminal in case one becomes lost or damaged during installation.

*OEM cross reference PN# 12521433916 - Commonly used for the crankshaft position sensor.

Please reference the original part number from the existing connector to confirm fitment, before ordering.

Suggested tools:

Suggested crimping pliers: T#387193
Wire De-pin tools:
12pc De-Pin Tool Set - T#386379
23pc De-Pin Tool Set - T#641943

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3 Pin Connector
10X Entries Into Our F80 M3 Sweepstakes 10X Entries For Our Spin To Win Sweepstakes!
ECS - Corporate Logo
T#:33412924
Part#: 12521433917
Ships on Jan 27, 2027
Sale - Save 14% $ 8.99

This product was last offered at the strikethrough price on
10-28-2026

$ 7.69 USD
Free Shipping on orders $49 and up
Sale - Save 14%
$ 8.99

This product was last offered at the strikethrough price on
10-28-2026

$ 7.69 USD
Free Shipping on orders $49 and up

Includes connector housing with terminals and seals. Commonly used for the camshaft position sensor.

ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need.

Each connector includes an additional terminal in case one becomes lost or damaged during installation.

*OEM cross reference PN# 12521433917 - Commonly used for the camshaft position sensor.

Please reference the original part number from the existing connector to confirm fitment, before ordering.

Suggested tools:

Suggested crimping pliers: T#387193
Wire De-pin tools:
12pc De-Pin Tool Set - T#386379
23pc De-Pin Tool Set - T#641943

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3 Pin Connector
10X Entries Into Our F80 M3 Sweepstakes 10X Entries For Our Spin To Win Sweepstakes!
ECS - Corporate Logo
T#:33412925
Part#: 12521433915
In Stock
Sale - Save 40% $ 10.99

This product was last offered at the strikethrough price on
11-07-2026

$ 6.59 USD
Free Shipping on orders $49 and up
Sale - Save 40%
$ 10.99

This product was last offered at the strikethrough price on
11-07-2026

$ 6.59 USD
Free Shipping on orders $49 and up

Includes connector housing with terminals and seals. Commonly used for the engine oil level sensor.

ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need.

Each connector includes an additional terminal in case one becomes lost or damaged during installation.

*OEM cross reference PN# 12521433915 - Commonly used for the engine oil level sensor.

Please reference the original part number from the existing connector to confirm fitment, before ordering.

Suggested tools:

Suggested crimping pliers: T#387193
Wire De-pin tools:
12pc De-Pin Tool Set - T#386379
23pc De-Pin Tool Set - T#641943

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Hitachi - Corporate Logo
T#:48850055
Part#: 12147518628
Ships in 2 Business Days
$ 71.99 USD
Free Shipping on orders $49 and up
The camshaft position sensor is essential for assisting the engine DME by monitoring the camshaft's position. The data from this sensor is key to optimizing ignition timing and ensuring smooth engine performance. Often referred to as the CMP sensor, this component is crucial for the overall functionality of the powertrain. A failing camshaft position sensor can cause a range of issues, including engine stumbling, hesitation during acceleration, power loss, and even starting difficulties or complete failure to start.
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Precision Raceworks - Corporate Logo
T#:38161695
Part#: 201-0360-RED
Ships in 9 Business Days
$ 5.99 USD
Free Shipping on orders $49 and up
Upgrade any wiring system with this optimal solution, ensuring reliability and durability in any demanding automotive application. Red in color and 12 Gauge.

Precision Raceworks - Corporate Logo
T#:38161703
Part#: 201-0360-BLU
Ships in 9 Business Days
$ 4.99 USD
Free Shipping on orders $49 and up
Upgrade any wiring system with this optimal solution, ensuring reliability and durability in any demanding automotive application. Blue in color and 12 Gauge.
Precision Raceworks - Corporate Logo
T#:38161710
Part#: 201-0362
Ships in 9 Business Days
$ 4.99 USD
Free Shipping on orders $49 and up
Upgrade any wiring system with this optimal solution, ensuring reliability and durability in any demanding automotive application. Black in color and 18 Gauge dual wire.

Precision Raceworks - Corporate Logo
T#:38161711
Part#: 201-0360-BLK
Ships in 9 Business Days
$ 4.99 USD
Free Shipping on orders $49 and up
Upgrade any wiring system with this optimal solution, ensuring reliability and durability in any demanding automotive application. Black in color and 12 Gauge.
Precision Raceworks - Corporate Logo
T#:38161698
Part#: 201-0360-ORG
Ships in 9 Business Days
$ 4.99 USD
Free Shipping on orders $49 and up
Upgrade any wiring system with this optimal solution, ensuring reliability and durability in any demanding automotive application. Orange in color and 12 Gauge.

Precision Raceworks - Corporate Logo
T#:38161687
Part#: 201-0361-GRN
Ships in 9 Business Days
$ 3.99 USD
Free Shipping on orders $49 and up
Upgrade any wiring system with this optimal solution, ensuring reliability and durability in any demanding automotive application. Green in color and 18 Gauge.

Precision Raceworks - Corporate Logo
T#:38161693
Part#: 201-0360-WHT
Ships in 9 Business Days
$ 4.99 USD
Free Shipping on orders $49 and up
Upgrade any wiring system with this optimal solution, ensuring reliability and durability in any demanding automotive application. White in color and 12 Gauge.
Precision Raceworks - Corporate Logo
T#:38161692
Part#: 201-0360-YEL
Ships in 9 Business Days
$ 4.99 USD
Free Shipping on orders $49 and up
Upgrade any wiring system with this optimal solution, ensuring reliability and durability in any demanding automotive application. Yellow in color and 12 Gauge.
2 Pin Connector
10X Entries Into Our F80 M3 Sweepstakes 10X Entries For Our Spin To Win Sweepstakes!
ECS - Corporate Logo
T#:33412928
Part#: 12521427615
In Stock
Sale - Save 35% $ 7.99

This product was last offered at the strikethrough price on
11-07-2026

$ 5.19 USD
Free Shipping on orders $49 and up
Sale - Save 35%
$ 7.99

This product was last offered at the strikethrough price on
11-07-2026

$ 5.19 USD
Free Shipping on orders $49 and up
Includes connector housing with terminals and seals. Commonly used for the engine oil pressure switch. ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need. Each connector includes an additional terminal in case one becomes lost or damaged during installation. *OEM cross reference PN# 12521427615 - Commonly used for the engine oil pressure switch. Please reference the original part number from the existing connector to confirm fitment, before ordering. Suggested tools: Suggested crimping pliers: T#387193 Wire De-pin tools: 12pc De-Pin Tool Set - T#386379 23pc De-Pin Tool Set - T#641943
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2 Pin Connector
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ECS - Corporate Logo
T#:33412932
Part#: 61132359999
In Stock
Sale - Save 40% $ 10.99

This product was last offered at the strikethrough price on
11-07-2026

$ 6.59 USD
Free Shipping on orders $49 and up
Sale - Save 40%
$ 10.99

This product was last offered at the strikethrough price on
11-07-2026

$ 6.59 USD
Free Shipping on orders $49 and up

Includes connector housing with terminals and seals. Commonly used for the coolant level sensor.

ECS Tuning replacement harness connectors include all necessary pins and wire seals for a complete harness repair. Whether you have a broken harness connector or need a complete wiring repair, we have the components you need.

Each connector includes an additional terminal in case one becomes lost or damaged during installation.

*OEM cross reference PN# 61132359999 - Commonly used for the coolant level sensor.

Please reference the original part number from the existing connector to confirm fitment, before ordering.

Suggested tools:

Suggested crimping pliers: T#387193
Wire De-pin tools:
12pc De-Pin Tool Set - T#386379
23pc De-Pin Tool Set - T#641943

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Hitachi - Corporate Logo
T#:48815470
Part#: 12141709616
Back Ordered
$ 32.99 USD
Free Shipping on orders $49 and up
NOTE: Does not include o-ring seal - see BMW # 12141748398 This is the crankshaft position sensor. It provides information for the ECU. A faulty sensor can cause issues with timing adjustment and limit performance and vehicle operation. Replace your sensor with a high-quality Hitachi sensor to restore peak performance.
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