Defect
On a small number of vehicles, a software problem could cause the emergency calling (eCall) system not to work properly when there's a crash or when the SOS button is pressed.
Safety Risk
If the eCall system doesn't work in an emergency situation, there could be a delay in response from emergency services.
Remedy
Mercedes-Benz will notify owners by mail and advise you to take your vehicle to a dealership to update the communication module software.