DTC Description
WARNING: This page is about a different car, the 2019 Hyundai Elantra. However, it is still accessible from the selected car via links, so may be relevant.
B121200 is set when LIN data from "FRONT PARKING ASSIST SENSOR RH (CENTER)" is not transmitted to "BCM" caused by the LIN communication line/the ultrasonic sensor fault or LIN data is abnormal.