General notes

If you cannot lock or unlock the vehicle with the SmartKey, either the battery in the SmartKey is discharged, the SmartKey is faulty or the starter battery is discharged.

SmartKey and replace it if necessary. Check the battery in the SmartKey and replace it if necessary.
mechanical key. Unlock the driver's door using the mechanical key.
mechanical key. Lock the vehicle using the mechanical key.
battery contacts checked at a qualified specialist workshop. Have the starter battery and the battery contacts checked at a qualified specialist workshop.

If the SmartKey is faulty, contact Roadside Assistance or a qualified specialist workshop.

    See also:

    Important safety notes
    WARNING It is dangerous to shift the automatic transmission out of parking position P or neutral position N if the engine speed is higher than idle speed. If your foot is not firmly on th ...

    Important notes
    In order to prevent the vehicle's battery from discharging, the interior lighting functions are automatically deactivated after some time except for when the SmartKey is in position 2 in the i ...

    BAS PLUS (Brake Assist System Plus)
    BAS PLUS is only available in vehicles equipped with DISTRONIC PLUS. Observe the "Important safety notes" section. At speeds above approximately 4 mph (7 km/h), BAS PLUS assists you ...