Based on Web information 1997 Toyota Camry LE V6 3 1MZFE has Two(2) O2 sensors (bank 1 Sensor one and two) before Catalyst convertor and One (1) O2 sensor after Catalyst convertor. Would please clarify if I have one or two O2 sensor before Catalyst convertor.

I have replaced new one (BOSCH 13354) before Catalyst convertor (in front of engine under hood) on Bank 1 Sensor 1(I think). The computer has been reset at Auto Parts Store. After resetting computer the engine signal goes away but it reappears next day. I am getting code P0135 "O2 Sensor Heater Circuit Malfunction". Car compuputer has been reset many times at different Auto Parts store but the engine light reappears next day.Would you please shed light why engine signal reappears in day or so even with new O2 sensor and resetting car computer. How I can solve engine light problem