8D0973822 I found a sensor with this part number on floor what is it for

 

You just "found it on the floor", like your b7 just shat it out?

 

It is a connector, not a sensor. Google the part number and you will see lots of info. Used in multiple ways in an Audi/VW to connect stuff (like the radio, etc...)

Either something that should work isn't anymore or it was an extra that someone stuffed under the dash (or had in the glove box and it got behind it under the dash and fell out).