The 4D is in the wiring harness. It can sense the start/stop indicator light and it can "push" the start/stop switch button. It remembers whether the start/Stop is on or off when the car is shut off. When the car is started the car automatically puts it "on", the 4D senses that it is different than when the car was shut off and turns start/stop back "off". So basically the car thinks that you have pressed the button to turn it off; that's why the message pops up on the dash. This is a great way to do things because there is no modification to the software like using the OBD tool and therefore there are absolutely no side effects even possible.