A Mercedes-Benz vehicle displays Transmission Not in Park Risk of Vehicle Rolling Away when the driver's door is not fully closed.
Open the driver's door and close it again to clear transmission, not in parking warning message on a Mercedes-Benz.
Don't open the driver's door while driving. Park the vehicle, set the parking brakes, open the driver's door, and close it again.
If you turn off the engine, make sure to move the gear selector to Park; otherwise, the vehicle will not start in Reverse or Drive.
While, in most cases, closing the driver's door will clear the transmission, not in park warning, there are cases when the warning message shows even if the door is closed.
Door is Open / Not Closed Properly
If the warning transmission not in park risk of the vehicle rolling away still comes up; you most likely have a faulty door latch. The door latches have a sensor inside that detects if the door is open or closed. Even if the door is closed, the door latch sensor can fail, making the car think you have the door open when the door is closed.
You will not get a door open (ajar) warning when the driver's door is open; instead, you get the red Transmission Not in P - Risk of Vehicle Rolling Away warning.
This warning is designed to alert a driver who may be stepping out of the vehicle when the transmission is in Drive, Reverse, or Neutral.
The instrument cluster can only show one warning at a time, which is Risk of Vehicle Rolling Away and beep, which is a higher priority warning than door is an open warning.
Car won't start
The car won't start if the transmission is not in Park or Neutral. Press the brake pedal, then the PARK button on the gear selector, and start the engine.
If the vehicle won't start, set the parking brake and chock at least one tire front and back to prevent the vehicle from rolling.
If the Transmission Not in Park Risk of Vehicle Rolling Away won't go away after you close the door or restart the engine, the vehicle will need to be diagnosed with a Mercedes-Benz scanner.
If the vehicle is still under warranty, visit any Mercedes-Benz dealer to have this problem resolved.
Otherwise, to troubleshoot this problem, you will need to read the fault codes with a Mercedes-Benz scanner. Possible problems include faulty ISM gear selector module, discharged battery, bad brake light switch.
As a temporary fix, disconnecting the battery for at least 5 minutes, then reconnect.