Mercedes W164 ML280 CDI OM642.940 Engine Control Unit ECU Kit A6421506691 Key

Mercedes W164 ML280 CDI OM642.940 Engine Control Unit ECU Kit is a factory-original electronic control module designed for the powertrain of the W164 M-Class model equipped with the OM642.940 diesel engine. Using an original ECU with a matched key ensures proper communication with the vehicle's electrical system, stable engine operation, and consistency with Mercedes' factory electronic architecture.

Specifications and technical data

• SKU: A6421506691-1
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A6421506691
• Substitutable numbers: A6421506691, A 642 150 66 91, 0281013384, 0 281 013 384, A1645450708, A 164 545 07 08
• Category: ECUs & Computer Modules

Purpose and function of the engine control unit

The presented engine computer is part of the Electronic control modules and controllers category, responsible for overseeing the operation of the OM642.940 unit in the Mercedes W164 ML280 CDI. The ECU analyzes sensor signals, manages fuel injection, controls the injection system, and regulates a range of actuators, which directly impacts engine refinement, performance, and fuel consumption. Using an original module ensures compatibility with factory control maps and proper integration with other vehicle systems, such as the immobilizer or comfort modules.

Advantages of using an original ECU with a key

The set includes the engine control unit along with the key, which in practice facilitates the adaptation process for a specific vehicle. For workshops and automotive electricians, this means a more efficient programming and matching procedure to the vehicle's installation. Compared to universal solutions or aftermarket replacements, the original Mercedes ECU module minimizes the risk of CAN bus communication issues, diagnostic errors, and malfunctions of anti-theft security systems.

The product comes from the used electronic components segment, which allows for a significant reduction in repair costs compared to purchasing a new controller, while maintaining the factory design and operating parameters. This is a practical solution for both professional service centers and individual users who want to restore full powertrain functionality without overstretching their budget.

Professional use in diagnostics and repairs

The engine computer designed for the ML280 CDI with the OM642.940 unit is suitable for:

• comprehensive repairs of the injection system and engine management,
• cases of original ECU damage due to power surges or water ingress,
• projects requiring the replacement of the controller-key set to restore communication with the immobilizer,
• advanced diagnostics when it is necessary to substitute a functional module for testing purposes.

Thanks to the preservation of the factory electronic architecture, the module allows for full utilization of factory diagnostic software and testers supporting the Mercedes brand. This is crucial for brand-specialized service centers that expect predictable controller behavior under various operating conditions.

Product condition and installation aspects

The offered controller belongs to the used parts group, meaning it has been removed from a vehicle and may show signs of wear that do not affect its functionality. Before installation, a standard diagnostic procedure and verification of compatibility with the specific vehicle configuration, including the model year, equipment version, and electrical system type, are recommended. In many cases, it will be necessary to perform appropriate programming or adaptation procedures at a specialized service center to ensure full cooperation with the vehicle's other modules.

Choosing a used ECU – knowledge for an informed purchase

When selecting a used engine computer for a Mercedes, it is worth paying attention to compatibility with the powertrain, electrical architecture, and software. It is good practice to consult with a mechanic or electrician who can confirm the suitability of a given module for a specific ML280 CDI unit. To better understand when used electronics are a reasonable solution and how to safely select a controller, comfort module, or sensors, it is worth reading the guide: The second life of electronics – when is it worth choosing used engine controllers, comfort modules, and parking sensors?

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 engine controllers, powertrain management modules, or electronic accessory control systems, check the available parts in the Mercedes electronic control modules and controllers category.

For those who want to further optimize the vehicle's downtime at the workshop and better plan repairs using a wide warehouse offer, the following article may also be helpful: No more waiting for weeks – how a wide assortment in one warehouse really shortens your car's downtime at the mechanic?