Originally Posted by dr.kent

I've read about several "fixes" for this ailment, however, all miss the true culprit. It is a rather common issue, not just with Mercedes, but with other makes, too. The problem lies in the ribbon wire that connects the main CD changer chassis with the optic control board mounted on the rear of the unit. Fortunately, the repair is quite simple. Remove the Cd changer, remove the two screws holding the rear mounted optic control board box. Release the ribbon cable from the optic board connector by sliding the two locking pins down away from the connector (toward the ribbon cable), then gently pull the ribbon cable free from the connector. Clean the ribbon cable end by lightly abrading with 600 grit emery cloth and wiping with alcohol. Reinsert cable in to connector, making sure it is fully seated, then firmly slide locking pins down(toward optic board). Reattach optic control board box to rear of changer and reinstall changer. In rare occaisons, the ribbon cable needs to be replaced and is available on eBay for about twenty bucks. This repair fixes a multitude of error messages... no magazine; no cd; no Cd changer; etc. I've performed this procedure on dozens of units, from Mercedes, Audi, BMW, Infiniti, etc with great success. Good luck!