Toyota Repair: Toyota Avalon 2000 P1130 ans P1135 codes, valve cover gasket, toyota avalon

Question
Where is the a/f sensor, rear manifold and how do I replace?  Would this be the same as replacing the O2 sensor socket? Where is that if so?
Thanks!

Answer
The sensor is located in the exhaust manifold near the center, it can be accessed from underneath but there are a lot of things in the way such as power steering lines and the sway bar etc, the O2 sensor socket will work, you can use a long extension on the socket or try removing it from the top, the electrical connector is visible just behind the valve cover gasket, anyway, it's not exactly easy to get to.