What FBS is
FBS (Fahrberechtigungssystem) is Mercedes' immobilizer. The key talks to the ignition module, called EIS or EZS. The key and the module share secret data.
FBS3
On FBS3 cars, the data can be read from the EIS. That lets us write a new key on site, even when all keys are lost. This covers most Mercedes from the late 1990s to around 2014, and some Sprinter-based commercial vans up to about 2018.
FBS4
FBS4 keys are made by Mercedes for the specific car. Outside tools can't create them reliably. If your car is FBS4, the dealer is the right place, and we'll tell you so.
How to tell which you have
Text us the year, model and a photo of the key. Model and build date usually settle it.
Worn ignition locks
Older Mercedes with high mileage often have worn locks. The emergency blade may need a few cuts to turn smoothly; we explain before charging for extra attempts.
Written by the Keyhub Locksmith team, a mobile car locksmith in Marietta, GA. Updated October 23, 2026.