[Oakleyguy]

As others have said, 90% chance it's a stone. Sometimes they get lodged in there really well. Try pushing the heat shield in multiple places, and also tapping on the heat shield with the handle (grip) of a screw driver.

Worked for me. Driving forward and reversing a few times can also do it.

Edit: Just realized I responded to an old post. I'mmmm dumb.