EWS
The early system. Key data in a separate EWS module. Common on E46, E39 and E53.
CAS
Car Access System, the main BMW system for over a decade: E60, E90, E70 and early F-series. Most CAS cars are done on site, including all keys lost.
FEM
Front Electronic Module, used on F30, F32, F15 and others. Key jobs often involve reading the module, which takes more time.
BDC
Body Domain Controller on later F-series and G-series. Newer versions are the most involved. Some jobs mean taking the module for bench work and returning with a finished key.
Why years overlap
BMW changed systems by model, not by year. A 2013 car can be CAS or FEM depending on the model. Text the model and year and we confirm.
Written by the Keyhub Locksmith team, a mobile car locksmith in Marietta, GA. Updated October 23, 2026.