See also:

Immobilizer
The immobilizer prevents your vehicle from being started without the correct SmartKey. When leaving the vehicle, always take the SmartKey with you and lock the vehicle. The engine can be started ...

Problems with your vehicle
If you should experience a problem with your vehicle, particularly one that you believe may affect its safe operation, we urge you to contact an authorized Mercedes-Benz Center immediately to ...

Locking the vehicle (mechanical key)
If the vehicle can no longer be locked with the SmartKey, use the mechanical key. Open the driver's door. Close the front-passenger door, the rear doors and the trunk lid. Press the locking ...