What is this sensor under front fender liner driver side

Parking sensor or collision sensor.

Made by Denso...does it have a part number or barcode on the other side?

 

I thought it was some type of beeper that you hear like when you push the remote to lock the doors or it was a sensor to help the remote unlock the doors when you're obviously outside the car something to help the remote get picked up quicker from a distance I had that hanging too on mine on an '04 '05 I just tucked it backed up in the mess I couldn't see where it should be slid onto a bracket or anything I really didn't try to figure out what it was and whatever it was I probably didn't need it It was just needed to stay plugged in and be up under the fender liner when the fender liner goes back in

 

If your car has SKS, then Tom's on the money there it is not a sensor – it is a beeper. I'm not sure where that should attach, but hopefully, it should be obvious. If the car suffered some damage in that area and the attachment point is no longer there, just zip-tie it to something out of the way to keep it from flapping about.