TSB - SERVICE ACTION: SHIFT QUALITY LOGIC IMPROVEMENT (SA315A) - This bulletin provides the procedure to improve the logic of the Transmission Control Unit (TCU) on some 2018MY Optima (JFa) 2.0T, produced from April 19, 2017 through July 10, 2017, and some 2018MY Sorento (UMa) 3.3L vehicles, produced from March 31, 2017 through July 25, 2017, which may experience a shift quality concern, such as a hard downshift, upshift, and/or shift delay.
