Mercedes W164 ML320 4-Matic OM642.940 Diesel Engine Unit ECU Kit A6421509478 Key

Mercedes W164 ML320 4-Matic OM642.940 Diesel Engine Unit ECU Kit is a control set designed for the powertrain with a diesel engine and automatic transmission. The set includes an electronic Engine Control Unit along with a key, which facilitates matching to a specific vehicle and reduces the risk of immobilizer issues. The product belongs to the Electronic control modules and controllers group, making it a consistent element of the vehicle's factory electrical architecture.

Specifications and technical data

• SKU: A6421509478-2
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A6421509478
• Substitutable numbers: A6421509478, A 642 150 94 78, 0 281 013 757, 0281013757, A1645451308, A 164 545 13 08
• Fuel type: Diesel
• Gearbox type: Automatic
• ECU type: Engine Control Unit
• Category: ECUs & Computer Modules

Purpose and function in the powertrain

The presented engine computer is the central module managing the operation of the diesel unit in the Mercedes W164 ML320 4-Matic model with the OM642.940 engine. It is responsible for precise control of fuel dosage, injection system operation, boost pressure, and cooperation with the automatic transmission, which translates into stable torque characteristics and correct response to load.

As a specialized controller from the Electronic control modules and controllers group, the ECU communicates with other vehicle modules via data buses, monitoring engine operating parameters and reacting to signals from sensors. Using a dedicated set with a key makes it easier to maintain compliance with the vehicle's factory security system.

ECU type, fuel, and transmission

The device belongs to the Engine Control Unit type, i.e., controllers responsible for comprehensive engine management. It has been designed to work with a diesel-powered unit, which means adapting control algorithms to the characteristics of compression ignition, high injection pressures, and the specifics of turbocharger operation.

Compatibility with the automatic transmission allows for smooth information exchange between the ECU and the transmission control module. This makes it possible to synchronize gear shift timing with the current engine load, which improves powertrain refinement and reduces unwanted jerking while driving.

Benefits of using a complete ECU + key set

Using a set that includes the engine computer and the key brings a number of practical benefits during repair or controller replacement:

• increased chance of seamless integration with the existing immobilizer system,
• reduced need for advanced programming compared to a "bare" controller,
• consistency of components coming from a single set, which facilitates diagnostics and configuration,
• possibility of effective vehicle repair after an engine electronics failure without interfering with the engine's mechanics.

The product is marked as Used, which in practice means it comes from dismantling, and its technical parameters are verified based on the manufacturer's specifications as well as part numbers and interchangeable numbers available in the specification section.

Selection, compatibility, and technical aspects

To correctly select this engine computer for a specific Mercedes vehicle, it is crucial to compare the OEM part number and available interchangeable numbers with the vehicle data – all this information can be found in the technical specification section. It is also worth paying attention to compatibility with the fuel type, transmission type, and the generation of the OM642.940 unit, which minimizes the risk of incompatibility.

For installation, it is recommended to use the services of a workshop with experience in Mercedes electronics, especially in the area of engine controller programming and key adaptation. This allows maintaining full functionality of safety systems and avoiding communication errors in the vehicle network.

Expansion of the control system and additional information

If you are planning a comprehensive repair or upgrade of the engine area in your Mercedes and need other components from the same group, such as controllers, management modules, or other ECU units, check the available parts in the Electronic control modules and controllers Mercedes category.

When making a decision about using a used controller, it is worth familiarizing yourself with practical tips regarding selection and installation. A detailed discussion of the topic, along with advice on ECUs, comfort modules, and parking sensors, can be found in the article The second life of electronics – when is it worth choosing used engine controllers, comfort modules, and parking sensors?.