When the automatic transmission shifts 2nd to 3rd it emits a very brief buzz or squeal. Does noise intermittently and transmission functions normally. No light for it , but does have code stored for trans malfunction, when scanned by high tech BMW scanner, my scan detected nothing. I would just live with it but wish to sell car and would like to resolve so can sell with good conscience. Was told the new plastic pan and filter combo warps leaks and car was likely driven low on fluid, so they filled. No change. 2 to 3rd Buzzzz for 2 seconds!