This TSB applies to all 2011-2012 Audi A8 and all 2012 A6 and A7 vehicles. While scanning the vehicle with GFF, the entry B120216 (reversible belt tensioner voltage too small) in address code 90 and 8F may be stored, and the vehicle has software version 060 or 070.
This is an incorrect diagnosis which can occur if different signals coincide within a very short time. According to Audi, the operation of the reversible belt tensioner is not affected by this fault code, and functions according to design intent.
The solution is to update with new software version 080, and then clear the fault code in GFF.