He recently was involved in the rebuilding of a ZF6HP transmission in a BMW vehicle. When it was installed and road tested, it ran perfectly and the vehicle was delivered to the customer. A few days later it came back in a failsafe condition. A scan tool retrieved several DTCs, all related to a slipping condition. After the codes were cleared, the vehicle drove well on a road test. However, a slight pump whine type of noise was heard. When they checked passing gear, the transmission slipped and aborted to a failsafe condition. Again, slip codes were retrieved.