Two problems related to transmission slip out of gear have been reported for the 2010 Audi S4. The most recently reported issues are listed below.
Mechatronic failure. Car was fully serviced and maintained by Audi however Audi will not pay for cost of replacement. Cost of replacement is $3,000 usd. Car displayed gearbox malfunction limited driving ability, parking brake failure then lost all drive and car was stuck in n. I was unable to shift out of gear and put the car in park this is a safety issue.
Mechatronics unit failed in the vehicle automatic transmission. Transmission failure message listed on car dashboard. Car would not shift out of 1st gear and there was no reverse gear. Car had to be towed to the dealership for repair. Multiple web forum posts stated the Audi b8 models suffered this failure frequently.