Collision Avoidance Sound

I used to get an audible warning with a red rear car icon on the control display when I would approach a car too fast. Now it is only the icon and no audible warning. I did take it into the dealer a few weeks ago but I'm not sure if that was the cause.
I looked at the settings and could not find anything related to sound warnings on collision avoidance. Any ideas how this change happened? I actually like the sound warning - can it be programmed back in or could it be a part malfunction?
thanks

According to the Driver's Guide, when approaching a vehicle rapidly, the red vehicle icon is displayed first. If the driver does nothing, the red vehicle icon flashes and an acoustic signal sounds. If the driver does nothing, the brakes will be applied automatically if the car's speed is less than ~35 mph. When this sequence of events begins depends on the front collision warning time set in iDrive. These settings are stored in driver profiles which are associated with each fob.

If the fob you are using now isn't the same fob that you used previously, the front collision warning settings could be different from what you expect.

If the system software in your i3 was updated during your dealer visit, you didn't backup your driver profiles before the software was updated, or you didn't restore your driver profiles after the software was updated, the front collision warning settings would be the default settings which might be different from those you prefer.

Maybe your front collision warning time needs to be increased. Maybe you haven't gotten close enough to the car ahead to trigger the flashing red vehicle icon and acoustic signal sound.