I'm getting a warning that the Driver's door is open even when closed. My mechanic says that the door closed sensor is embedded in the latch. The entire door latch must be changed. Does anyone know an alternate repair to this door closed sensor?

The only other thing that has worked in my experience with other vehicles -- not specifically a Mercedes -- was to spray a penetrating lubricant inside the door latches on each door, then open and close the door many times repetitively. It is possible that the switch in the latch may be binding, and may loosen and begin to work again by trying this. Otherwise, replacing the latch is the only solution.

Unfortunately on that specific model Mercedes the switch is located in the latch and can only be replaced with a whole new latch. Its actually very odd because the switch looks like it can easily be replaced. I haven't found just the switch however, so you're stuck with the entire latch.