DAUGHTER'S ,07 R56, 123k miles. Transmission was operating fine, one day while driving on highway, she went to exit and car will would not downshift automatically nor manual. Car was taken to BMW mechanic, Codes, 00A0B6(CAS:Selector-lever interlock), 004F81(EGS: Neutral position in D), 002D52(DME: Super knocking,( 002DCB(DME:Fuel shut off due to superknocking , cyl. 2). Where to start? And is it even worth attempting? Car has reverse, starts fine, no forward gears or its stuck in 5th gear. Mechanic is saying replace transmission. There was and are no clunking of gears before or presently. Could it possibly be low fluid or clogged valve body? She loves her Sherlock, but can not invest another 2k in a trans. Thanks all.

 

You could run some trans flush snake oil thru it. What do you have to lose?

 

You should take it to a transmission shop that specializes in Aisin 09G automatic transmissions. It is the same transmission used in many Volkswagen models.
You may get lucky and only need a valve body and a transmission flush. These transmissions need to have their fluid changed every 50,000 miles, regardless of what the factory says.