BMW CAS3 Semi-Intelligent Remote Car Key Fob for 315MHz, 433MHz & 868MHz Frequencies

This product is a replacement remote car key designed for BMW vehicles equipped with the CAS3 (Car Access System) immobiliser system. It serves as a direct substitute for lost, damaged, or non-functioning original keys, providing the necessary electronic and physical components to regain access and ignition capability for your car. Described as 'semi-intelligent', this key fob contains the internal electronics required for remote central locking and, once programmed, for vehicle ignition, but it arrives as a universal blank. This means it must be professionally tailored to your specific BMW by cutting the metal blades and electronically programming the fob to match your car's unique security code and chosen radio frequency.

Features and Construction

The key is built to match the specifications of the original BMW HU92 part number, ensuring physical and electronic compatibility with a range of BMW models. Its construction utilises two primary materials to fulfil different roles within the key's design.

Material and Build

The internal components and the key blades are made from metal copper. This material is chosen for its excellent electrical conductivity, which is essential for the key's electronic transponder chip to communicate with the car's immobiliser ring, and for its durability, allowing the key blade to be cut precisely and to withstand the mechanical stress of turning in the ignition and door locks. The outer casing of the key fob is moulded from plastic. This housing protects the internal circuit board and battery, provides a comfortable grip, and carries the button layout for remote functions. The blend of metal and plastic results in a functional key that balances internal electrical performance with external practicality.

Size and Practical Fit

The source text does not provide exact dimensional measurements for the key fob. However, it is designed as a direct replacement for the original BMW HU92 key, meaning its form factor should match the size, shape, and button placement of the factory key. This ensures it fits comfortably in hand and in pockets. A notable practical feature is that it is supplied with three separate physical key blades attached to the single fob. This provides spare blades that can be stored securely, offering a contingency should one blade become damaged or worn over time, without needing to reprogram the entire electronic fob unit.

Uses and Placement

This key is intended for a specific scenario: replacing an existing key for a BMW with a CAS3 system. Its use is not for adding extra keys unless the original programming data is available, but primarily for restoring full vehicle access when a key is missing or broken.

Event or Professional Use

The primary use case involves professional automotive locksmiths or BMW dealership service departments. They will use this blank key as the base component to create a fully functional vehicle key. The process involves two main steps: firstly, cutting the metal copper key blade to perfectly match the unique pattern of your BMW's door and ignition locks; secondly, using specialist diagnostic equipment to programme the key's electronic transponder and remote frequency to synchronise with your specific vehicle's CAS3 immobiliser and central locking receiver. This ensures the key will not only physically turn but also electronically authenticate to start the engine.

Everyday Home Use

Once professionally cut and programmed, this key fulfils the same everyday role as the original. It allows the user to unlock the car doors remotely via the buttons on the fob, insert the blade into the door or boot lock manually if needed, and turn the ignition to start the vehicle. The choice of frequency (315MHz, 433MHz, or 868MHz) is determined by the region and model year of your BMW, and selecting the correct option is crucial for the remote signal to be received by the car. Having a correctly programmed spare key also provides peace of mind against being locked out due to a single key failure.

Benefits and Buying Value

Purchasing this blank replacement key offers a practical solution that can be more cost-effective than sourcing a key directly from a BMW main dealer, especially for older models. Its value lies in providing the core hardware needed by a specialist to restore your vehicle's accessibility.

Reuse and Low Maintenance

The key itself, once programmed, requires minimal maintenance typical of any remote key fob: periodic replacement of the internal coin battery to maintain remote function. The inclusion of three metal blades offers a form of reusability and preparedness; if one blade becomes bent or worn, a spare is already attached and can be cut to match the original pattern without any electronic reconfiguration. The plastic casing can be wiped clean if dirty, but like all electronic fobs, it should be protected from excessive moisture and impacts.

Why Choose This Product

This product is chosen when you need a replacement key for your BMW and have access to professional programming services. Its advantages include clear compatibility (CAS3 system, HU92 number), the flexibility of three radio frequency options to suit different BMW models and regions, and the practical benefit of having three key blades on a single fob. It provides all the necessary raw materials—the correctly specified electronics in a matching shell and durable metal blanks—for a locksmith to create a fully operational key, making it a practical and informed purchase for this specific automotive need.