back up sensors

[RiverSide]

park assist stopped working.
i did a search and checked the sensors they all click fast.
When i push the park assist button in P the light will go off,but as soon as i put in reverse the light comes on.
Pushed the button in R but the light stays on.

i checked the owners guide,...
does anybody know what to do next?

[antileno]

I have same issue. I know that if one fails they all fail but is there any way to text each sensor individually and replace only one or do you have to replace all of them?