Sienna 2000 - Code P1130

The engine light came on and the code is P1130, according to the code reader the problem is the Air fuel sensor, does any one knows where is this located. I am confused too because another description for this code came as

P1130 Toyota A/F Sensor Circuit Range/Performance Malfunction (Bank 1 Sensor 1)

Any ideas?
Thanks,

I have codes P1130, P1135 and P1153. I wish I could find step-by-step diagrams on how to clean or replace the air fuel sensors.