In the C4 it is the case that there is a warning tone if someone does not strap on and the buckle sign also lights up. I have now had several times that a passenger had not strapped on and there was no beep or symbol. Only if the passenger straps off while driving it beeps and the symbol is there. Can someone understand or explain what it has on them? In the driver’s seat everything is as planned: instant beep tone and sign on the display. Before wi a few shouting out: the passenger’s non-fastening was only for testing and only for a few seconds