Spec-Auto – KEY / EZS Read Info FBS4 Data protocol

Spec-Auto – KEY / EZS Read Info FBS4 Data Protocol is a diagnostic/bench-level automotive function used for working with modern Mercedes-Benz immobilizer and authorization systems.

What it does

This protocol is designed to read identification and security-related data from:

• EZS / EIS (Electronic Ignition Switch) – the vehicle’s immobilizer “brain”
• KEY (smart key / key data)

It is specifically aimed at FBS4 sy

Typical use cases

• Key programming workflows (lost key situations)
• ECU / EZS synchronization tasks
• Module replacement or cloning in authorized repair environments
• Diagnostic verification of immobilizer faults