TSB: SERVICE ACTION: TCU UPGRADE ? DRIVING PERFORMANCE IMPROVEMENT (SA251) - This bulletin provides information related to the Transmission Control Unit (TCU) software upgrade for some 2017MY Sorento (UMa) 2.0T-GDI vehicles produced from April 7, 2016 to October 27, 2016 for a logic improvement. To apply the improved logic, the TCU should be reprogrammed using the GDS/KDS download, as described in this bulletin.