RX-300 O2 Sensors-How Many?

[charbaby]

I own an 01 Lexus RX-300 that has a CEL/VSC on. When I have the OBD scanned free at Auto Zone, the codes come up different each time. I've cleared the codes on several occations. Does anyone know just how many O2 sensors there are on this vehicle? I count 3...Bank 1 sensor 1, Bank 2 sensor 1 and one just after the cat converter. The dealer just replaced the cat converter under the 8yr 80000 mile converter warranty and the codes are reading different again. Also, I can't seem to find any help from other web sites as far as the location of these sensors, only the code #'s which I already know. Any information is appricated.

 

[ChiTDI]

They may call them a/f sensors (air/fuel) in the exhaust manifolds. The one and only O2 sensor may be behind the cat downstream in the exhaust pipe. I was pricing them for maintenance replacement - $250 and up each. Ended the early replacement theory.