DTC P2120: Throttle/pedal Position Sensor/Switch "D" Circuit, DTC P2122: Throttle/pedal Position Sensor/Switch "D" Circuit, DTC P2123: Throttle/Pedal Position Sensor/Switch "D" Circuit High Input: Notes
WARNING: This page is about a different car, the 2004 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
HINT:
There are the repair procedure for the "accelerator pedal position sensor".