BMW Electrical Sensors, Switches, & Relays for BMW Z4 M Roadster S54 (2003-2008)

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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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Turner Motorsport - Corporate Logo
T#:597496
Part#: 014579TMSKT
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Turner Motorsport - Corporate Logo
T#:391751
Part#: 014579TMS
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All vehicles will lose some degree of performance due to heat soak under the right operating conditions.  Engine management systems constantly monitor operating conditions and modifying parameters based on sensor inputs. BMW integrated the intake air temp sensor in the MAF housing on models such as the E39 M5, and, being sandwiched behind a hot radiator and in some applications next to an even hotter valve cover, this is less than ideal for performance applications. Absorbing excess heat from its surroundings, the MAF can’t shed it fast enough, and the ECU reads an inaccurately high intake air temperature. Compensating for this false hot air measurement, the ECU pulls timing and runs a richer fuel mixture, resulting in a significant loss of torque.

What can you do?  Locate an intake air temp sensor in a location where it can properly measure incoming air temps and where it's less prone to heat soak. Mounting the sensor further away from the heat source and isolating it from the MAF housing, it can both resist the effects of heat soak longer and respond to temperature changes more quickly.  The result is you’ll experience reduced torque loss and more consistent power output when you’re pushing your engine hard. 

The Turner engineering team was initially skeptical of the claimed performance benefits of this modification. They first set out validate the functionality and performance benefit of a temp sensor relocation. Replicating stop-and-go traffic heat soak in a 2001 540i was a simple task in a controlled environment - their dynometer. First the car was heat soaked to simulate being stuck in traffic or moving at low speeds by running the car four times on the dyno with the dyno's cooling fans disabled. The fans were then turned on for three more runs to observe the recovery rate once air flow was reintroduced. The test: following this procedure once with a stock IAT, and once with their relocation kit in place. 

The result? Turner recovered 11lb-ft torque at 2500rpm through use of their relocation kit, with even greater recovery to be found for M5 owners. Here are the heat soak-related torque losses Turner experienced:

Stock IAT location:
18rwtq at 2500rpm
10rwtq at 3000rpm
9rwtq at 3700rpm

Turner IAT Relocation:
7rwtq at 2500rpm
5rwtq at 3000rpm
5rwtq at 3700rpm

**Click here for installation instructions**

The Turner engineering team designed a complete plug and play kit (unlike all other options on the market) that makes for quick, easy, and reversible installation. Weather-sealed connectors keep out the elements, while sheathed wiring offers a clean appearance underhood. With a harness nearly 3 feet long - the Turner IAT relocation kit offers flexibility in positioning, but not too long that you're left with unsightly excess wiring. Turner recommends positioning the sensor in a location away from engine heat, but still within the intake ducting to achieve accurate intake temp readings - such as the far side of the base of the airbox. Vehicles with cold air intakes with cone-style filters can even position the sensor in the end of the filter. Simply drill a hole in your (cool) location of choice and plug in the harness. More information including installation instructions and some good examples of sensor mounting locations can be found in our DIY PDF. 

We include everything you need to relocate your IAT, just select your desired sensor brand below - Genuine BMW or original equipment Beru.

Also the perfect plug-n-play option for anyone looking to upgrade their intake to utilize an Alpha-N tune!

Note for vehicles with M62 engine: applicable to 1999 and up

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Turner Motorsport - Corporate Logo
T#:638071
Part#: 014579TMSKT1
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This product was last offered at the strikethrough price on
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$ 113.24 USD
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What can you do to get rid of this heat soak? Turner designed an IAT relocation kit that moves the intake air temp sensor to a cooler location. Mounting the sensor further away from the heat source and isolating it from the MAF housing, it can both resist the effects of heat soak longer and respond to temperature changes more quickly. The result is you’ll experience reduced torque loss and more consistent power output when you’re pushing your engine hard.
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ECS - Corporate Logo
T#:49996974
Part#: 059235LA01
In Stock
New Item
Sale - Save 20% $ 29.99

This product was last offered at the strikethrough price on
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$ 23.99 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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Braille - Corporate Logo
T#:558037
Part#: B14115
Ships in 5 Business Days
$ 204.99 USD
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When building a car for the track, one of the most important factors to consider is weight. Stock batteries can weigh up to almost 50 pounds and are unnecessarily large, designed to power a host of systems not normally used in a track car (radios, lighting, etc.). What can you do to cut weight the weight without affecting your cars operation? This is where Braille Battery comes in with their long line of performance lightweight battery options! Designed to provide the highest cranking power possible while being up to 75% lighter, Braille Battery is one of the foremost leaders in automotive racing batteries with nothing but high quality, high output batteries in mind!
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OEM Starter Motor - E46 M3 2001-2006
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Valeo - Corporate Logo
T#:2988
Part#: 12417835735
In Stock
$ 400.99

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

$ 293.99 USD
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$ 293.99 USD
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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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Braille - Corporate Logo
T#:558038
Part#: B2015
Ships in 7 Business Days
$ 237.99 USD
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When building a car for the track, one of the most important factors to consider is weight. Stock batteries can weigh up to almost 50 pounds and are unnecessarily large, designed to power a host of systems not normally used in a track car (radios, lighting, etc.). What can you do to cut weight the weight without affecting your cars operation? This is where Braille Battery comes in with their long line of performance lightweight battery options! Designed to provide the highest cranking power possible while being up to 75% lighter, Braille Battery is one of the foremost leaders in automotive racing batteries with nothing but high quality, high output batteries in mind! The B2015 is Braille's most popular non-carbon racing battery and is able to start larger engines easily for racing and offers daily driving capability for most 4 and 6 cylinders engine vehicles. Physical Specifications: BCI Group: All sizes Weight: 15lbs / 6.8kg Length: 6.8" / 173mm Width: 3.4" / 86mm Height: 6.1" / 155mm Polarity: Right Side Positive Performance Specifications: Voltage: 12 Full Charge Voltage: 13.2 Pulse Cranking Amps (PCA): 1067 Amp Hour (AH): 21 Life Cycle @ 10% DOD: 3100 *THIS BATTERY REQUIRES A CUSTOM MOUNTING SOLUTION. The size and weight are significantly smaller than a stock battery and will not be held in place by the stock battery mount*
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Bremmen Parts - Corporate Logo
T#:36913379
Part#: 12147539171
In Stock
Sale - Save 20% $ 89.99

This product was last offered at the strikethrough price on
05-03-2026

$ 71.80 USD
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Sale - Save 20%
$ 89.99

This product was last offered at the strikethrough price on
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$ 71.80 USD
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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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Braille - Corporate Logo
T#:558042
Part#: B3121
Ships in 6 Business Days
$ 270.99 USD
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When building a car for the track, one of the most important factors to consider is weight. Stock batteries can weigh up to almost 50 pounds and are unnecessarily large, designed to power a host of systems not normally used in a track car (radios, lighting, etc.). What can you do to cut weight the weight without affecting your car's operation? This is where Braille Battery comes in with their long line of performance lightweight battery options! Designed to provide the highest cranking power possible while being up to 75% lighter, Braille Battery is one of the foremost leaders in automotive racing batteries with nothing but high quality, high output batteries in mind! The B3121 battery from Braille is their lightest do-everything battery available, offering 1380 pulse cranking amps that can crank over V8 engines with ease while still coming in at under 22 pounds, half of the weight of a standard Group 34 battery! This is thanks to their Advanced AGM racing technology that allows them to put a ton of power into a very small package. Physical Specifications: BCI Group: All sizes Weight: 21lbs / 9.5kg Length: 6.6" / 168mm Width: 5.2" / 132mm Height: 6.8" / 173mm Polarity: Right Side Positive Terminal Type: Steel terminal block with M6 bolt Performance Specifications: Voltage: 12v Recharge Voltage: 14.4V – 14.6V Maintenance charge voltage: 13.8V 5s Pulse Cranking Amps (PCA): 1380 10s PDC: 124 Amp Hour (Ah): 31 Watt Hour (Wh): 372 Life Cycle @ 10% DOD: 3100 Charging Temperature 0C to 50C Discharge Temperature range -40C to +60C Storage temperature -40C to +60C *THIS BATTERY REQUIRES A CUSTOM MOUNTING SOLUTION. The size and weight are significantly smaller than a stock battery and will not be held in place by the stock battery mount*
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Braille Performance Intensity Carbon Lithium-ION Battery - i48CX - 10...
This item is classified as Hazardous Materials and requires special shipping and handling. We cannot ship this item out of the US or with priority shi
Braille - Corporate Logo
T#:558047
Part#: I48CX
Ships in 4 Business Days
$ 1,164.99 USD
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The ultra-lightweight, standard height I48CX lithium-ION battery from Braille Battery is a popular choice among BMW enthusiasts looking for a drop-in replacement battery that shaves off a ton of weight, 35 pounds in total! Thanks to the Group 48 design of this battery, no modifications are needed for installation. This is perfect for anyone looking to drive their car both on and off of the track, without any negative side effects, and wants a battery with a 10-15 year life span!
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Braille - Corporate Logo
T#:36947237
Part#: B48-H6-L3
Ships in 4 Business Days
$ 398.99 USD
$ 398.99 USD
Alternator - 150 Amp - Valeo
We Price Match - Give Us A Call or Chat!
Valeo - Corporate Logo
T#:579634
Part#: 439590
In Stock
$ 620.35

This product was last offered at the strikethrough price on
05-03-2026

$ 518.99 USD
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$ 620.35

This product was last offered at the strikethrough price on
05-03-2026

$ 518.99 USD
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Valeo Brand New Alternator - E89 Z4 M Coupe/Roadster
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Valeo - Corporate Logo
T#:379218
Part#: 12317837691KT
Ships in 5 Business Days
$ 378.99 USD
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$ 378.99 USD
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This is a brand new Valeo alternator. BMW Alternators are built especially for extremes of heat, cold and high demand. Your BMW deserves nothing less than the best, which is why an OEM Valeo alternator is the best option. BMW alternators are built to last using the highest quality materials and the most technologically advanced processes. All alternator parts are 100% factory tested to assure that they meet or exceed original equipment specifications. And every alternator is fully load tested to guarantee compliance with BMW's strict performance specifications. 

No core charge!

Fits the following BMW Chassis:

E89 BMW Z4 M Coupe, M Roadster

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Braille - Corporate Logo
T#:558046
Part#: G30
Ships on Aug 7, 2026
$ 522.99 USD
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The G30 lithium battery from Braille is designed for the Import Tuner market (4 and 6 cylinder) for track use and has enough power for small black V8 race cars and hot rods with light electrical demands/accessories and standard compression. The G30 comes in the popular ETX 30 Group size, just like the B3121 AGM, so it is small and light enough to mount in a variety of locations. Incorporated in this battery is the same technology used in their race winning batteries used by nearly every OEM developer in classes ranging from SCCA to Formula 1.
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ECS - Corporate Logo
T#:33412924
Part#: 12521433917
In Stock
Sale - Save 18% $ 10.99

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$ 8.99 USD
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$ 8.99 USD
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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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ECS - Corporate Logo
T#:40072446
Part#: LK2M
In Stock
Sale - Save 29% $ 6.99

This product was last offered at the strikethrough price on
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$ 4.94 USD
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$ 6.99

This product was last offered at the strikethrough price on
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$ 4.94 USD
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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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ECS - Corporate Logo
T#:33412918
Part#: 12521732596
Ships in 1-2 days
Sale - Save 25% $ 10.99

This product was last offered at the strikethrough price on
06-14-2026

$ 8.24 USD
Free Shipping on orders $49 and up
Sale - Save 25%
$ 10.99

This product was last offered at the strikethrough price on
06-14-2026

$ 8.24 USD
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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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ECS - Corporate Logo
T#:33412947
Part#: 12521433916
In Stock
Sale - Save 25% $ 10.99

This product was last offered at the strikethrough price on
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$ 8.24 USD
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Sale - Save 25%
$ 10.99

This product was last offered at the strikethrough price on
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$ 8.24 USD
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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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ECS - Corporate Logo
T#:33412925
Part#: 12521433915
In Stock
Sale - Save 25% $ 10.99

This product was last offered at the strikethrough price on
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$ 8.24 USD
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Sale - Save 25%
$ 10.99

This product was last offered at the strikethrough price on
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$ 8.24 USD
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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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ECS - Corporate Logo
T#:33412928
Part#: 12521427615
Ships in 1 Business Day
Sale - Save 25% $ 7.99

This product was last offered at the strikethrough price on
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$ 5.99 USD
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Sale - Save 25%
$ 7.99

This product was last offered at the strikethrough price on
06-14-2026

$ 5.99 USD
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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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ECS - Corporate Logo
T#:33412932
Part#: 61132359999
In Stock
Sale - Save 25% $ 10.99

This product was last offered at the strikethrough price on
06-14-2026

$ 8.24 USD
Free Shipping on orders $49 and up
Sale - Save 25%
$ 10.99

This product was last offered at the strikethrough price on
06-14-2026

$ 8.24 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

Show More Show Less