TSB - SERVICE ACTION: 2.4L SHIFT QUALITY & WAKE-UP LOGIC IMPROVEMENT (SA316B) - This bulletin provides the procedure to improve the logic of the Electronic Control Unit (ECU) and Transmission Control Unit (TCU) on some 2018MY Optima (JFa) 2.4L, produced from April 18, 2017 through September 7, 2017, and some 2018MY Sorento (UMa) 2.4L vehicles, produced from March 31, 2017 through October 19, 2017, which may experience an extended crank and/or a shift quality concern, such as a hard downshift, upshift, and/or shift delay.
