Buy OEM 2003 Lexus Part # 6911053020 (69110-53020). Door Lock Actuator Motor (Right, Front). Door Lock Actuator - Repair or Replace Your 2003 Lexus may need a new door lock

ACTUATOR ASSY, FRONT DOOR LOCK, RH

Fits IS 300

Door Lock Actuator - Repair or Replace
Your 2003 Lexus may need a new door lock actuator if your keyless entry doesn't work or your lock button doesn't lock the doors.