Looking at pictures and diagrams and am not sure which one it is. Don't want to replace the wrong sensor.
OBD code PO1135. A/F ratio sensor, bank 1, sensor 1. on 1999 Lexus ES300
Bank 1 sensor 1 is located between engine and firewall. Additional information on P01135 is located at link below. Click on link, or copy and paste web address to your upper address bar, and click the go button.