One problem related to transmission sensor has been reported for the 2010 Audi S4. The most recently reported issues are listed below.
Vehicle's transmission became non-operational while driving on the highway. This was due to multiple failed sensors in the "s tronic transmission integrated sensors" module. Early sensor failure has been a known issue as Audi issued TSB 35 12 08 2032211/1 on December 21, 2012 (only 3 years after original model production began) outlining the problem. The failure causes an obvious safety hazard and no recall has been issued.