Crankshaft Position Sensor

If your vehicle is struggling to start once warmed up, this is likely the culprit.

Mfg Part #: 0021539028 0021539028
ECS Part #: ES#5396160
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Product Details

The legendary Mercedes-Benz M103 and M104 inline-6 engines—powering iconic 1980s and 1990s chassis like the W124 300E, R129 300SL, and W140 S320—are celebrated for their incredible durability. To manage the ignition timing on these classic powerplants, Mercedes utilized the EZL (Elektronische Zündanlage) electronic ignition system. The absolute heart of this system is the rear-mounted Engine Crankshaft Position Sensor, commonly referred to as the EZL Sender.

Mounted deep at the back of the engine block near the transmission bellhousing, this magnetic sensor reads the flywheel to determine the exact rotational speed and Top Dead Center (TDC) of the engine. It sends this critical pulse directly through a long coaxial cable to the EZL ignition module mounted on the driver's side inner fender. Over three decades of absorbing extreme under-hood heat and engine vibration, the internal magnetic coil and the thick insulation on the sensor's wiring degrade. When the coil shorts out or the wire shielding cracks, the EZL module loses its RPM signal and instantly cuts the spark, bringing your classic Mercedes to a dead stop.

Common Signs of a Failing M103/M104 EZL Crankshaft Sensor:

Stalling When Warm: This is the hallmark of a failing CPS on these classic inline-6 engines. The sensor may work perfectly when you leave the driveway, but internally short-circuit as the engine reaches operating temperature, causing the vehicle to suddenly stall in traffic.
No Start Condition: If the EZL module does not receive a clear RPM pulse from the sensor during cranking, it will not fire the ignition coil. The engine will crank strongly and endlessly, but refuse to start.
Dead Tachometer: On these specific chassis, the EZL module drives the tachometer based on the signal from this sensor. A tachometer needle that stays completely dead while you are cranking a no-start engine is a massive clue that the EZL sender has failed.
Expensive Misdiagnoses: A failing EZL sender mimics the exact symptoms of a dead EZL ignition control module.

ECS Tuning Recommends for Classic Mercedes Owners: Never replace a highly expensive (and often hard to find) EZL ignition module without testing and replacing this rear crankshaft sensor first! A dead sensor is the most common cause of a no-spark condition on the M103 and M104.

Tech Tip: Do not confuse this sensor with the front TDC sensor mounted near the harmonic balancer. The front sensor is strictly for diagnostic equipment. This rear sensor (OE # 0021539028) is the one required to actually run the engine. Pay close attention to how the long coaxial wire is routed along the firewall to the EZL; keep it securely clipped away from the hot exhaust manifold.

Essential Tools & Hardware for the Job

Replacing the rear EZL sender is an essential DIY that will save you a massive towing bill, but because the sensor is notoriously buried between the firewall and the back of the cylinder head, having the right tools is the difference between a 30-minute repair and a weekend of frustration. We highly recommend adding these items to your ECS Tuning cart:

Schwaben Locking Flex-Head Ratchet & Extension Set (ECS Part #: ES#3184421): You will be working completely blind behind the engine block. A long, flexible extension and a flex-head ratchet are absolutely mandatory to reach the 5mm Allen mounting bolt without having to remove major intake components.
Schwaben 100-Piece Specialty Bit Kit (ECS Part #: ES#2500878): This comprehensive kit ensures you have the exact metric Allen (Hex) bit needed to extract the mounting bolt. Stripping this bolt back by the firewall will turn a simple job into an engine-out nightmare.
CRC QD Electronic Cleaner (ECS Part #: ES#2804752): The coaxial connection port on the EZL module is often exposed to dirt and moisture. Spray out the module-side connection thoroughly before threading on your new sensor cable to ensure a perfect micro-voltage signal.

This Part Fits the Following Vehicles

Make	Model	Submodel	Engine	Year	Chasis	Special Fitment Notes
Mercedes Benz	300CE	Base	L6 3.0L	1988	124.050	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	All	L6 3.0L	1988	124.050	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	Base	L6 3.0L	1988	All	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	All	L6 3.0L	1988	All	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	Base	L6 3.0L	1989	124.050	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	All	L6 3.0L	1989	124.050	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	Base	L6 3.0L	1989	All	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	All	L6 3.0L	1989	All	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	Base	L6 3.0L	1990	124.051	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	All	L6 3.0L	1990	124.051	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	Base	L6 3.0L	1990	All	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	All	L6 3.0L	1990	All	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	Base	L6 3.0L	1991	124.051	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	All	L6 3.0L	1991	124.051	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	Base	L6 3.0L	1991	All	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	All	L6 3.0L	1991	All	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	Base	L6 3.0L	1992	124.051	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	All	L6 3.0L	1992	124.051	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	Base	L6 3.0L	1992	All	Use vehicle selector to confirm fitment
Mercedes Benz	300CE	All	L6 3.0L	1992	All	Use vehicle selector to confirm fitment
Mercedes Benz	300E	Base	L6 3.0L	1986	124.030	Use vehicle selector to confirm fitment
Mercedes Benz	300E	All	L6 3.0L	1986	124.030	Use vehicle selector to confirm fitment
Mercedes Benz	300E	Base	L6 3.0L	1986	All	Use vehicle selector to confirm fitment
Mercedes Benz	300E	All	L6 3.0L	1986	All	Use vehicle selector to confirm fitment
Mercedes Benz	300E	Base	L6 3.0L	1987	124.030	Use vehicle selector to confirm fitment
Mercedes Benz	300E	All	L6 3.0L	1987	124.030	Use vehicle selector to confirm fitment
Mercedes Benz	300E	Base	L6 3.0L	1987	All	Use vehicle selector to confirm fitment
Mercedes Benz	300E	All	L6 3.0L	1987	All	Use vehicle selector to confirm fitment
Mercedes Benz	300E	Base	L6 3.0L	1988	124.030	Use vehicle selector to confirm fitment
Mercedes Benz	300E	All	L6 3.0L	1988	124.030	Use vehicle selector to confirm fitment
Mercedes Benz	300E	Base	L6 3.0L	1988	All	Use vehicle selector to confirm fitment
Mercedes Benz	300E	All	L6 3.0L	1988	All	Use vehicle selector to confirm fitment
Mercedes Benz	300E	Base	L6 3.0L	1989	124.030	Use vehicle selector to confirm fitment
Mercedes Benz	300E	All	L6 3.0L	1989	124.030	Use vehicle selector to confirm fitment
Mercedes Benz	300E	Base	L6 3.0L	1989	All	Use vehicle selector to confirm fitment
Mercedes Benz	300E	All	L6 3.0L	1989	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.0L	1988	126.024	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.0L	1988	126.024	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.0L	1988	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.0L	1988	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.0L	1989	126.024	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.0L	1989	126.024	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.0L	1989	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.0L	1989	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.0L	1990	126.024	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.0L	1990	126.024	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.0L	1990	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.0L	1990	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.0L	1991	126.024	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.0L	1991	126.024	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.0L	1991	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.0L	1991	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.2L	1992	140.032	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.2L	1992	140.032	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.2L	1992	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.2L	1992	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.2L	1993	140.032	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.2L	1993	140.032	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	Base	L6 3.2L	1993	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SE	All	L6 3.2L	1993	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	Base	L6 3.0L	1990	129.061	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	All	L6 3.0L	1990	129.061	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	Base	L6 3.0L	1990	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	All	L6 3.0L	1990	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	Base	L6 3.0L	1991	129.061	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	All	L6 3.0L	1991	129.061	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	Base	L6 3.0L	1991	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	All	L6 3.0L	1991	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	Base	L6 3.0L	1992	129.061	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	All	L6 3.0L	1992	129.061	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	Base	L6 3.0L	1992	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	All	L6 3.0L	1992	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	Base	L6 3.0L	1993	129.061	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	All	L6 3.0L	1993	129.061	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	Base	L6 3.0L	1993	All	Use vehicle selector to confirm fitment
Mercedes Benz	300SL	All	L6 3.0L	1993	All	Use vehicle selector to confirm fitment
Mercedes Benz	S320	LWB	L6 3.2L	1994	140.033	Use vehicle selector to confirm fitment
Mercedes Benz	S320	SWB	L6 3.2L	1994	140.032	Use vehicle selector to confirm fitment
Mercedes Benz	S320	SWB	L6 3.2L	1994	140.043	Use vehicle selector to confirm fitment
Mercedes Benz	S320	SWB	L6 3.2L	1994	140.051	Use vehicle selector to confirm fitment
Mercedes Benz	S320	SWB	L6 3.2L	1994	140.057	Use vehicle selector to confirm fitment
Mercedes Benz	S320	SWB	L6 3.2L	1994	140.134	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1994	140.032	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1994	140.033	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1994	140.043	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1994	140.051	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1994	140.057	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1994	140.134	Use vehicle selector to confirm fitment
Mercedes Benz	S320	LWB	L6 3.2L	1994	All	Use vehicle selector to confirm fitment
Mercedes Benz	S320	SWB	L6 3.2L	1994	All	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1994	All	Use vehicle selector to confirm fitment
Mercedes Benz	S320	LWB	L6 3.2L	1995	140.033	Use vehicle selector to confirm fitment
Mercedes Benz	S320	SWB	L6 3.2L	1995	140.032	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1995	140.032	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1995	140.033	Use vehicle selector to confirm fitment
Mercedes Benz	S320	LWB	L6 3.2L	1995	All	Use vehicle selector to confirm fitment
Mercedes Benz	S320	SWB	L6 3.2L	1995	All	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1995	All	Use vehicle selector to confirm fitment
Mercedes Benz	S320	LWB	L6 3.2L	1996	140.033	Use vehicle selector to confirm fitment
Mercedes Benz	S320	SWB	L6 3.2L	1996	140.032	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1996	140.032	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1996	140.033	Use vehicle selector to confirm fitment
Mercedes Benz	S320	LWB	L6 3.2L	1996	All	Use vehicle selector to confirm fitment
Mercedes Benz	S320	SWB	L6 3.2L	1996	All	Use vehicle selector to confirm fitment
Mercedes Benz	S320	All	L6 3.2L	1996	All	Use vehicle selector to confirm fitment
Mercedes Benz	SL320	Base	L6 3.2L	1994	129.063	Use vehicle selector to confirm fitment
Mercedes Benz	SL320	All	L6 3.2L	1994	129.063	Use vehicle selector to confirm fitment
Mercedes Benz	SL320	Base	L6 3.2L	1994	All	Use vehicle selector to confirm fitment
Mercedes Benz	SL320	All	L6 3.2L	1994	All	Use vehicle selector to confirm fitment
Mercedes Benz	SL320	Base	L6 3.2L	1995	129.063	Use vehicle selector to confirm fitment
Mercedes Benz	SL320	All	L6 3.2L	1995	129.063	Use vehicle selector to confirm fitment
Mercedes Benz	SL320	Base	L6 3.2L	1995	All	Use vehicle selector to confirm fitment
Mercedes Benz	SL320	All	L6 3.2L	1995	All	Use vehicle selector to confirm fitment

*The above product applications have been written by ECS Tuning. All warranties, product application, fitment, and performance are the responsibility of ECS Tuning. For additional information see the terms of use.

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ECS Tuning now offers an online returns solution! To get started, simply log into your ECS Tuning account, Click the "View Orders" button on the My Account home page and select the order that you wish to make a return on to begin. If you have any questions, feel free to reach out to our Customer Service Team for assistance!

Please note: Refunds will be processed to the original payment method used on the order or to an in store credit, respective to the type of return that is made as well as any pre-existing arrangements with an ECS Tuning Customer Service Representative. In the event that multiple forms of payment were used, we will refund the value to an in store credit. In the event that a return label is provided, these charges may be deducted from the total refund you receive.

Original shipping costs are non-refundable and the buyer is responsible for return shipping charges. ECS Tuning will not accept COD deliveries.

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Free Shipping On Orders $49 & Up

Items marked with a 'Free Shipping On Orders $49 and Up' logo may qualify for free standard economy ground shipping to the contiguous United States (48 states) for most orders with a value greater or equal to $49.00 USD. Oversized products and direct ship products are excluded from this offer unless otherwise noted.

Free Shipping

Items marked as 'Free Shipping' may qualify for free standard economy ground shipping to the contiguous United States (48 states). Oversized products and direct ship products are excluded from this offer unless otherwise noted.

The policies listed above are subject to change at any time without notice.

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Why You Should Shop From ECS Tuning

ECS Tuning stands out as more than an automotive parts supplier-it's a vibrant community fueled by a shared passion for cars. Born from the enthusiasm of car lovers, we offer an unmatched understanding and commitment to the automotive world, providing high-quality parts and accessories sourced from our own experiences. Our selection is meticulously crafted to meet the highest standards of performance, quality, and design, catering to both the latest trends and classic styles.

Our distinct advantage lies in our passionate team and comprehensive support, offering expert advice and seamless service from selection to installation. Shopping with ECS brings exclusive perks, including our Lifetime Replacement Guarantee and free shipping on orders over $49, enhancing the value of every purchase. As a central hub for car enthusiasts, ECS Tuning fosters a rich community where ideas and experiences flourish, transforming us from a mere supplier into a platform where automotive dreams come to life.

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At ECS Tuning, we understand that plans can change. That's why we offer a flexible cancellation policy for our customers. You may cancel your order at any time before you receive the shipment confirmation. This policy is designed to provide you with peace of mind and the flexibility to make adjustments to your purchases as needed. Should you decide to cancel your order, simply reach out to our customer service team, and we will assist you with the process swiftly and efficiently.

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