Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If any other codes are displayed other than DTC P1129, diagnose and repair those codes first. If only DTC P1129 is displayed, check throttle body assembly for binding or other problem. Repair or replace as necessary. If throttle body assembly is okay, replace ECM.