BMW key programming is often misunderstood. You cannot program a used BMW key fob to start a different BMW. This is due to the EWS (Engine Immobilizer System) encryption being VIN (Vehicle Identification Number) specific. Only BMW has access to the database containing the encrypted ISN (Individual Serial Number) linked to each vehicle. New BMW keys must be ordered from a dealership’s parts department after providing proof of ownership and VIN. The key is then ordered, shipped to the dealership, and finally given to the purchaser.
The FZV (Central Locking System) and DWA (Anti-theft Alarm Siren System) operate independently from the EWS. They function differently and control the locking, unlocking, and alarm features of the key.
On some older BMW models (E series), a used or another remote might be programmable to lock/unlock and arm/disarm the vehicle. This is only possible if the remotes operate on the same radio frequency (315 MHz in North America and 433 MHz in Europe). However, even if programmed for these functions, the key will still not start the car.
The EWS transponder chip within the key is a write-once component. Even with aftermarket software or hardware capable of retrieving the ISN from the DME (Digital Motor Electronics) and EWS control modules, you would still need to write that data to a brand new EWS transponder chip. The EWS transponder is typically soldered to the internal circuit board of the key fob, making it extremely difficult to replace.
