Where is bank2 sensor 1 located on a Lexus RX300?

The "bank" or head considered number two in your vehicle will be closest to the front of the vehicle. The O2/AF Sensor

labeled 1st from that bank will be between the engine and the fan assembly. Pop the hood look down between the engine and

the bumper and you should see a thick wire (several actually just wrapped to look like one) going from the right side of

the engine to the exhaust pipe. It will end at a conical sensor with a Hex base.