What's this circular trim piece supposed to hold?
 

It's on the front bumper inside of the turn/cornering lights. The driver side has a roundish insert but the pax side has nothing. At first I thought it was missing its opposite counterpart but looking at some pics of other '13 G's, it appears the panel has a crisscross insert. Does this crisscross thing do anything? Or is it just a part of the circular trim piece? The 3rd pic shows the back of the circular trim piece, and the bottom tab is broken. But it doesn't look like there is a missing covering (the crisscross pattern), so that leads me to believe that the crisscross thing is an actual functioning part.

I can't find menti9n of this in the owners manual. Any help is much appreciated.
https://cimg2.ibsrv.net/gimg/www.mbw...380d6c04b.jpeg
https://cimg3.ibsrv.net/gimg/www.mbw...270194261.jpeg
https://cimg4.ibsrv.net/gimg/www.mbw...3aef176ac.jpeg
https://cimg5.ibsrv.net/gimg/www.mbw...e24a9153c.jpeg

That's the ambient air temp sensor housing. The crisscross is just a grille to let air hit the sensor. Passenger side is usually blank unless your car has the sensor on the driver side only. The broken tab is why it's loose. Nothing missing.

Thanks! Your comment in bold is a bit confusing to me. To help me understand, is there a sensor on the pax side, somewhere further back if I have a crisscross grill? If I don't have a crisscross grill, then it's supposed to be open because the ambient air sensor housing is only on the driver side?