Genuine OEM 2789050000 - Ignition Knock (Detonation) Sensor

Product Overview

This Genuine OEM 2789050000 ignition knock sensor is engineered to Mercedes-Benz factory specifications for precise detonation detection across a broad range of V8-powered models from 2011 to 2019. The sensor monitors engine knock and communicates with the engine control module to optimize ignition timing, protecting your engine from damage caused by premature detonation. Designed for Mercedes-Benz S-Class (W221, W222), E-Class (W212, W213), CL-Class (C216, C217), CLS-Class (C218), G-Class (W463), GL-Class (X166), GLE-Class (W166, V167), and SL-Class (R231) models, this OEM part ensures factory-level reliability and performance. Trust Genuine OEM parts to maintain your vehicle's engine management integrity.

Symptoms of a Failing Ignition Knock Sensor

• Check Engine Light illuminated with knock sensor-related diagnostic trouble codes (P0325, P0326, P0327, P0328)
• Engine pinging or knocking sound under acceleration or load
• Loss of power and reduced throttle response
• Rough idle or hesitation during acceleration
• Poor fuel economy due to retarded ignition timing
• Engine running in limp mode or reduced performance mode

Cross Reference Numbers

This Genuine OEM 2789050000 sensor is equivalent to or replaces the following part numbers: 2789050000, 278905000, 278-905-00-00.

Vehicle Compatibility

This sensor fits the popular models below. For Fitment Confidence, please use the vehicle selector tool above to verify exact compatibility for your vehicle.

• Mercedes-Benz S-Class S550 4.7 V8 Gas (W222): 2012–2017
• Mercedes-Benz S-Class S563 AMG 5.5 V8 Gas (W222): 2011–2013
• Mercedes-Benz S-Class S550 4.7 V8 Gas (W221): 2011
• Mercedes-Benz CL-Class CL550 4.7 V8 Gas (C216): 2011–2014
• Mercedes-Benz CL-Class CL63 AMG 5.5 V8 Gas (C216): 2011–2013
• Mercedes-Benz E-Class E550 4.7 V8 Gas (W212): 2012–2016
• Mercedes-Benz E-Class E63 AMG 5.5 V8 Gas (W212): 2012–2013
• Mercedes-Benz CLS-Class CLS550 4.7 V8 Gas (C218): 2012–2017
• Mercedes-Benz CLS-Class CLS63 AMG 5.5 V8 Gas (C218): 2012–2016
• Mercedes-Benz G-Class G63 AMG 5.5 V8 Gas (W463): 2014–2018
• Mercedes-Benz GL-Class GL550 4.7 V8 Gas (X166): 2013–2016
• Mercedes-Benz GL-Class GL63 AMG 5.5 V8 Gas (X166): 2013–2016
• Mercedes-Benz GLE-Class GLE63 AMG 5.5 V8 Gas (W166, V167): 2016–2019
• Mercedes-Benz GLS-Class GLS550 4.7 V8 Gas (X167): 2017
• Mercedes-Benz GLS-Class GLS63 AMG 5.5 V8 Gas (X167): 2018–2019
• Mercedes-Benz SL-Class SL550 4.7 V8 Gas (R231): 2013–2019
• Mercedes-Benz SL-Class SL63 AMG 5.5 V8 Gas (R231): 2013–2018
• Mercedes-Benz SLK-Class SLK55 AMG 5.5 V8 Gas (R172): 2012–2015
• Mercedes-Benz Maybach S550 4.7 V8 Gas (W222): 2017

This may also fit other applications. Please use the vehicle selector tool to verify fitment.

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Frequently Asked Questions

How do I know if my Mercedes-Benz knock sensor needs replacement?

The most common indicator is a Check Engine Light paired with knock-related diagnostic codes such as P0325 (Knock Sensor Circuit), P0326 (Knock Sensor Range/Performance), P0327 (Knock Sensor Low Input), or P0328 (Knock Sensor High Input). You may also notice audible engine knock or pinging under acceleration, especially when using lower-octane fuel or driving uphill under load. Some owners report a loss of power or the engine entering limp mode. A professional scan tool can confirm which knock sensor circuit is faulting.

Can I replace the knock sensor myself, or do I need a professional?

Knock sensor replacement is moderately accessible for experienced DIY technicians, though access varies by engine and model year. Most sensors are located on or near the engine block and require basic hand tools, a socket set, and sometimes a sensor socket. However, Mercedes-Benz engines are tightly packaged, and some sensors may require removing intake manifolds, valve covers, or other components. After installation, the vehicle typically requires a professional diagnostic scan to clear fault codes and verify proper sensor function. If you are not confident in your abilities, professional installation is recommended.

Why does my Mercedes-Benz S-Class or E-Class have multiple knock sensors?

Most Mercedes-Benz V8 engines, including those in the S-Class (W221, W222), E-Class (W212, W213), and other models in this fitment range, use two knock sensors to monitor detonation across both sides of the engine. This dual-sensor design provides better detection accuracy and allows the engine control module to make more precise adjustments to ignition timing. If one sensor fails, the other may continue to function, but the engine will run in a reduced-performance state until both are functioning properly. Always verify your specific model's sensor count before ordering.

What is the difference between a knock sensor and a mass air flow sensor?

A knock sensor detects mechanical vibrations caused by detonation (engine knock) and sends a signal to the engine control module to retard ignition timing and prevent engine damage. A mass air flow (MAF) sensor measures the volume and density of air entering the engine to help calculate the correct fuel injection amount. They are entirely different components serving different functions. A faulty knock sensor will trigger knock-related codes and audible engine knock, while a faulty MAF sensor typically causes rough idle, hesitation, and poor fuel economy codes. Do not confuse the two when diagnosing engine issues.

Is this Genuine OEM sensor better than an aftermarket knock sensor?

Genuine OEM parts are manufactured to Mercedes-Benz factory specifications and are engineered for exact fitment and calibration with your vehicle's engine control module. They carry the same warranty coverage as parts installed at a Mercedes-Benz dealership and ensure that knock detection sensitivity and response timing are optimized for your specific engine. Aftermarket sensors may be less expensive but can exhibit tolerance variations that affect knock detection accuracy. For a critical component like a knock sensor that protects your engine from detonation damage, a Genuine OEM part provides the highest assurance of reliability and performance.

Can a failing knock sensor cause transmission problems?

While a knock sensor itself does not directly control the transmission, a faulty sensor can indirectly affect transmission behavior. If knock sensor codes are present, the engine control module may enter limp mode, which can trigger the transmission to operate in reduced-performance mode or fixed gear selection. Additionally, if the sensor is not properly detecting knock and ignition timing is not being adjusted, the engine may run rough or hesitate, which the transmission control module may interpret as a drivability issue. Always address knock sensor faults promptly to prevent secondary effects on other systems.

Frequently Asked Questions

What is the cost of replacing a knock sensor on a Mercedes-Benz?

The cost of knock sensor replacement varies by model, engine location, and whether additional components must be removed for access. Parts cost for a Genuine OEM knock sensor typically ranges from moderate to mid-range, depending on your specific vehicle. Labor costs at a dealership can be substantial if intake manifolds, valve covers, or other engine components must be removed. Shopping for parts at eEuroparts.com and having the work performed by an independent shop can reduce overall costs while maintaining quality standards.

Order Genuine OEM 2789050000 today. In-stock orders ship same or next business day from our U.S. warehouse, and our fitment team is one call away if you need help confirming the right part for your Mercedes-Benz.

Note: All information on this page and in the FAQ is for general reference only. Verify fitment and consult a professional as needed. eEuroparts.com is not responsible for incorrect part selection or installation.