NHTSA Complaint #11650171 — 2015 HYUNDAI SONATA

While traveling on local roads and highways the vehicle transmission randomly down-shifts one or two gears. This has occurred when traveling in any gear from gears 3 through 6. It probably doesn't happen in 2nd gear because that is a transitory gear and not a cruising gear. After quickly moving the shifter from automatic mode into manual mode and then back into automatic mode the transmission returns to the proper gear. However sometimes it has down shifted again in as little as 30 to 60 seconds after resetting the shifter. This has been happening for years. The dealership has been unable to fix it. Because it is random, the issue is not readily reproducible by the repair shop. Sometimes it has happened several times within a 15 minute period. Sometimes it has occured multiple consecutive days. Other times a week or two has passed with no incident.