Confirmed with my scanner and with the Kiatechinfo.com
Code No.P0720 Output shaft speed sensor system
If the output from the output shaft speed sensor is continuously 50% lower than the vehicle speed for 1 second or more while driving in 3rd or 4th gear at a speed of 30 km/h or more, it is judged to be an open circuit or short-circuit in the output shaft speed sensor and diagnostic trouble code No.P0720 is output. If diagnostic trouble code No.P0720 is output four times, the transmission is locked into 3rd gear or 2nd gear as a fail-safemeasure.
Malfunction of the output shaft speed sensor
Malfunction of the transfer drive gear or driven gear
Malfunction of connector
Malfunction of the TCM
Test the input shaft speed sensor located below the torque converter.
This of course requires removal of the transmission.