Question

2001 Lexus IS300 3.0L with engine codes P1125 and P1129. how do you correct this?

Answer 1

P1125 Open or short in the throttle control motor

P1129 Electric throttle control system

This is going to be either going to be the ECM at fault or the ETC (electric throttle control). But what is between these two. is the harness to the motor. Check and inspect for any pins that is loose at the connection, then clear the code if P1129 return and this is the only code , you more than likely will solve this with a ETC replacement.