Originally Posted by TLSGuy15

Call me crazy, but I this is one of those rare instances when hitting the thing works. Litterally hitting right above the CD player a few times with the bottom of your fist works.
Other times I've found that sticking your fingers into the CD slot and moving the little CD door that opens and closes will clear it up.

I got my car used and the error always kept happening until I giured out it's a mechanical problem, hence why simply turning it off doesn't do anything.