What is the reason for the sudden decrease in the locking sound of a Mercedes-Benz?

[PatrickFitz]

You can check the central console settings to provide feedback on the locking sound and see if the setting is turned on or muted. Another possible reason is that "one of the doors is not fully closed." Below is some relevant information: 1. Automatic Door Locking While Driving: Automatic door locking while driving, also known as speed-sensing automatic locking, is an electronic device that automatically presses the door lock button when the vehicle reaches a preset speed to prevent accidental opening of the door. The preset speed is usually set by the manufacturer, typically between 10-20 km/h. 2. Function: When the vehicle reaches the preset speed, the lock button is automatically pressed to prevent accidental door opening. This is the most common automatic locking method used in many car models (such as Volkswagen, Audi, BMW, Mercedes-Benz, Hyundai, etc.). There are other methods of automatic door locking while driving. For example, when the transmission is shifted to D (Drive) gear, the lock button is automatically pressed to prevent accidental door opening. Some models from Chevrolet and Buick use this locking method.