There are actually three O2 sensors on Avalons:
bank 1 sensor 1 - Firewall side of the engine, harder to get to but you can see it from the driver's side.
bank 2 sensor 1 - Located between the engine and the fan/rad (very easy to see when you pop the hood). The cable is connected to a fluid check stick (originally).
bank 1 sensor 2 - Located immediately after the catalytic converter.
bank 1,sensor 1 oxygen senor by exhaust manifold
bank 1 is the one closest to the firewall. sensor 1 is the first one exhaust gasses will come in contact with after leaving the cylinder head.
On a 2000 Toyota Avalon, Bank 1 Sensor 1 (O2 sensor) is located on the exhaust manifold on the driver's side of the engine. It is positioned before the catalytic converter and is responsible for monitoring the oxygen levels in the exhaust gases. To access it, you may need to lift the vehicle and work from underneath or reach it from the top of the engine compartment. Make sure to disconnect the battery before attempting any repairs.
bank 1 sensor 1 2002 on toyots sienna
on cylinder 1 side mounted on the manifold
Bank 1 is the bank that sits closest to the front of the vehicle. Bank one is the bank with cylinder # 1. You have 4 oxygen sensors, (bank 1 sensor 1, bank 1 sensor 2, bank 2 sensor 1 and bank 2 sensor2). Follow the exhaust from the head of bank 1. The first sensor you come to is sensor 1, the second is sensor 2.
There are 3 oxygen sensors in total for the 96 avalon. Bank 2 sensor 1 is the one on the exhaust headers closest to the radiator. Bank 1 Sensor 1 you cant really see it, it is closest to the cabin. Peer from the drivers side and under the intake manifold and you should see it. Bank 1 and 2 Sensor 2 is under the car right after the cat converter.
its where the #1 cylinder is that's bank one
Bank 1 would be the bank of cylinders that contains the number 1 cylinder. Bank 1 sensor 1 would be the first O2 sensor in the exhaust leaving the bank 1 cylinder head and before the bank 1 catalytic converter.
before cat
Bank 2 is the side of the engine that faces the front of the vehicle, sensor 1 is the upper sensor, it is in the exhaust manifold
Trouble code P0170 means:Fuel trim malfunction (Bank 1)