I know there was glass or clear plastic or whatever in there before...I popped my head under the hood this evening to start trying to diagnose a very very bad oil leak that has curbed my car until I figure it.....the window is gone.

Does that happen a lot? It needs to be there, right?!

 

i have never seen one gone, but anything is possible I suppose.

It may simply be inside the sensor itself, and simply gluing it back will suffice.

If its gone out via the top, its gone, and you will need to make one out of clear plastic in my opinion.

I believe it should be there to keep crud out of that sensor, again, my opinion.