Is the function of this piece a wheel well liner holder or for some other use?There is a screw that goes underneath. Here's a picture from the ground, facing up.
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These pieces are installed by the dealer before they sell the car. A bunch of us have had issues with them, including me. Usually the clip falls out and allows the piece to swing out and hit the tire. Oddly, your clip stayed in and it looks like you lost the screw. Dealer should cover this if it's still under warranty.