Pedestrian Warning System
The Pedestrian Warning System causes Model S to emit sound when driving below approximately 32 km/h (19 mph), or while driving in reverse. Electric vehicles operate quietly and this sound helps to alert pedestrians of your oncoming vehicle. The sound, which activates whenever Model S is shifted out of Park, gets louder as speed increases.
If sound cannot be heard, pedestrians may not be aware of your oncoming vehicle, which may increase the likelihood of a collision resulting in serious injury or death. If the Pedestrian Warning System is not operating, immediately contact Tesla.