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BMW Electrical Sensors, Switches, & Relays for BMW E21 320i M10 1.8L

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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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OEM Bosch Voltage Regulator (Bosch Alternator) - 12311726022 ...

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T#:19326

Part#: 12311726022

In Stock at Vendor

$ 71.99

This product was last offered at the strikethrough price on
01-28-2026

$ 62.99 USD

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$ 62.99 USD

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This is the voltage regulator found on the back of the alternator. It's a normal wear item and the contacts are the first thing to check if you believe the alternator is not charging the battery (lights flickering or dim, battery light on in the dash, the engine quits without warning, or other electrical failures). The voltage regulator manages the voltage flowing through the car, especially to and from the battery. There are two carbon contacts on the regulator that control the magnetic field when the alternator is spinning and these contacts wear over time. A new set of contacts will be about 13mm in length. Anything less than 5mm and the voltage regulator should be replaced, regardless if that is the cause of your electrical problems or not. Most older mechanics will tell you to keep a spare regulator in your toolbox.

The carbon contacts can be replaced on their own but requires desoldering the old ones from the base and then soldering the new ones on. It may be easier to just replace the unit as a whole.

This is the OEM voltage regulator, made by Bosch or Hella. It's the one with the white base and fits most Bosch alternators from 1977-1995 (Valeo and other alternators look very different and have a black cover and base). This part number replaces the previous BMW part numbers - 12311271664, 12321279548, 12311722755, 12321711399 and Bosch part numbers 1197311021 and 1197311028.

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Hella 5-Prong Fuel Injection Relay - E21, E23, E24, E28, E30, E34 ...

T#:7175

Part#: 12631708646

In Stock at Vendor

$ 21.99

This product was last offered at the strikethrough price on
05-07-2026

$ 20.99 USD

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$ 20.99 USD

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This part has been superseded to BMW Part 12631708647

Hella Hella Horn - High Tone

T#:592707

Part#: 2768551

In Stock

$ 30.99 USD

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$ 30.99 USD

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Disc Type High-Tone, 12 V, 400 Hz with Bracket

Hella Hella Horn - Low Tone

T#:590880

Part#: 2768082

In Stock

$ 36.99 USD

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$ 36.99 USD

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Disc Type Low-Tone, 12 V, 335 Hz with Bracket

Hella Air Horn Kit

T#:592708

Part#: 3001651

In Stock at Vendor

$ 143.99

This product was last offered at the strikethrough price on
05-07-2026

$ 139.99 USD

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$ 139.99 USD

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Get noticed with this air horn kit from Hella!

Hella Horn - High-Tone

T#:592716

Part#: 7424011

In Stock

$ 17.99 USD

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$ 17.99 USD

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Upgrade the sound of your BMW or MINI with the Hella Horn - High-Tone. This high-quality horn delivers a powerful and attention-grabbing sound, enhancing safety on the road. Designed for easy installation, it provides a quick and effective way to improve the audible presence of your vehicle.

Powerful and attention-grabbing sound
Enhances safety on the road
Easy installation for convenience
Compatible with BMW and MINI models
High-quality construction for durability

Enhance the audible presence of your BMW or MINI with the Hella Horn - High-Tone, ensuring you're heard when it matters most.

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Hella Relay

T#:592718

Part#: 965400001

Ships in 10 Business Days

$ 14.99 USD

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$ 14.99 USD

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12V 30A SPST relay with bracket

Hella Horn - Low-Tone

T#:28869559

Part#: 7424001

In Stock

$ 17.99 USD

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$ 17.99 USD

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Universal fit. Not direct fit.

OEM Bosch Starter Relay - E21 320i

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T#:583822

Part#: 61311243207

In Stock at Vendor

$ 4.99 USD

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$ 4.99 USD

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This is a brand new starter relay from OEM supplier Bosch. If you have replaced your starter and have ruled out every other issue, this relay could restore your starters operation and get your car back up and running.

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15A Fuse - Priced Each

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T#:375327

Part#: 61131372626

In Stock at Vendor

$ 2.03 USD

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$ 2.03 USD

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Temperature Sensor

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T#:29898445

Part#: 13621362599

In Stock at Vendor

$ 283.99

This product was last offered at the strikethrough price on
04-10-2026

$ 265.99 USD

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$ 265.99 USD

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Genuine BMW Temperature-Time Switch

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