2002 Camry SE 3.0LV6 P1135 Code Which Air/fuel or oxygen Sensor is it? I have four sensors, 2 upstream and 2 downstream. All have different part numbers. I am guessing Downstream, rear. Can anyone confirm or deny and why?

 

Bank 1, Sensor 1.

Bank 1 is the rear bank of cylinders closest to the firewall. Sensor 1 is the first sensor on the exhaust system coming off the head.

If replacing the sensor suggest Denso or Toyota brand plus NOT to use a universal type.

These sensors can fail, not uncommon.

Sometimes the fault is to due to something else such as design issues. If so there might be a technical service bulletin (TSB) on this car which may relate to your problem. The dealer would have the info. The car is out of warranty thus even if a problem covered by TSB the dealer will charge you. But suspect the part is bad as any TSB issues would have shown up years ago.