BMW E81 E87 LCI E90 120d 320d N47 177HP ECU KIT DDE 7811700 CAS3 Keys Automatic

BMW E81 E87 LCI E90 120d 320d N47 177HP ECU KIT DDE 7811700 CAS3 Keys Automatic is a complete, used electronic set designed for BMW powertrains with an automatic transmission. It includes the engine control unit and the CAS module with a key, which allows for consistent operation of the immobilizer system and engine management in accordance with factory standards. This solution is particularly useful when replacing a damaged ECU or during advanced vehicle electronics repairs.

Specifications and technical data

• SKU: 7811700-4
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 7811700
• Substitutable numbers: 13618506199, 8506199, 13617811700, 7811700, 13618512587, 8512587, 02810150438, 0281015043, 61359147220, 9147220, 13617812500, 7812500, 13617812000, 7812000, 13617810000, 7810000, 13617809000, 7809000, 13617808401, 7808401, 13617807827, 7807827, 13617807530, 7807530, 13617807200, 7807200, 13617807142, 7807142, 13617806699, 7806699
• Gearbox type: Automatic
• Category: ECUs & Computer Modules

Purpose and function of the ECU + CAS kit

The presented set is part of the Electronic control modules and ECUs group, responsible for precise engine control and start authorization. Combining the ECU with the CAS module and a matched key ensures data consistency, which facilitates restoring the vehicle's proper operation after electronics failure or issues with the immobilizer.

In BMW E81, E87 LCI, and E90 series vehicles, such a set allows for maintaining proper communication between the powertrain, security system, and other comfort modules. This is especially important in cars equipped with an automatic transmission, where the engine control unit works with the transmission electronics, influencing the smoothness of gear shifts and the overall refinement of the system.

Benefits of using a complete set

Using a ready-made ECU set with a CAS module and key limits the need for complex programming and minimizes the risk of incompatibility between individual electronic components. In practice, this means:

• consistency of immobilizer and engine control unit data,
• easier adaptation in the vehicle compared to a single, "bare" ECU,
• preservation of the security system integrity,
• the ability to efficiently restore full vehicle functionality after electronics failure.

For workshops specializing in BMW and for informed users, this means a more predictable repair process and a lower risk of issues with starting the car after installation. It is a technically organized solution that is beneficial in terms of labor time.

Integration with BMW powertrain and electronics

The ECU included in the set works with the factory CAN network architecture in BMW vehicles, coordinating the operation of the engine, auxiliary systems, and – in the case of automatic versions – gear shift logic. The CAS module is responsible for key authorization, start signal management, and communication with other body modules. As a result, the entire set creates a coherent, logically linked system that, after proper installation and configuration, allows for restoring the factory operation of the vehicle.

In practice, this translates into stable starting, predictable throttle response, and proper cooperation with other electronic systems. The ECU kit with CAS key is therefore a key element for major repairs of control electronics in these BMW generations.

Condition, verification, and application in service practice

The item comes from a used vehicle and is intended for reinstallation by the customer or a specialized workshop. Before installation, a standard diagnostic procedure and matching the configuration to the specific car is recommended, in accordance with BMW service practice. This type of set is particularly useful in situations where the existing ECU has been damaged, communication issues with the immobilizer have occurred, or errors preventing the engine from starting have appeared.

By choosing this product, you receive a base for professional powertrain electronics repair, which – when installed correctly – allows you to restore the vehicle to full operational efficiency without the need for deep interference in the structure of factory security systems.

If you are planning a comprehensive repair or upgrade of the control electronics area in your BMW and need other elements from the same group, such as comfort modules, light control units, or engine management units, check the available parts in the BMW electronic control modules and ECUs category.

For a better understanding of how important it is to use original electronic modules in modern premium cars, it is worth reading an article describing the impact of properly selected components on the vehicle's character – you can find it here: Audi and emotions in their purest form – how used parts help maintain the brand's DNA.