Air Fuel Ratio Sensor 2002 Toyota Camry

2002 Toyota Camry
I am trying to replace all of the exhaust sensors on my 2002 Toyota Camry 3.0 6 cyl. SE model (California emissions) including the air fuel ratio sensor and oxygen sensors. I have replaced 3 of the 4 sensors. I do not know the location of the 4th sensor nor do I know if it can be replaced from the top of the car (like the air fuel ratio sensor you can see from the top, or is it located underneath? I have replaced the air fuel ratio sensor which is the one easily visible looking at the engine to the right. The other 2 you can see the connectors from the front of the engine looking down but you remove them from the bottom of the car toward the front of the car underneath . I don’t know where the 4th one is and most important, how do I replace it from the top? underneath? toward the front? in the back? Thanks, Frank


According to the parts store this vehicle has one air fuel ratio sensor and two oxygen sensors. So if you have replaced all three, your done or are we. Looking at the engine compartment diagram it would appear as though there are four sensors, two A/F sensors and two O2 Sensors. On most v6 engines there are 2 upstream(before the catalytic converter) and one downstream(after the convertor).

Air Fuel Ratio Sensor location diagram

air fuel ratio sensor