That code is Bank 2 Sensor 2 alright - it's the o2 sensor which is on the exhaust right under the right hand (Your passenger) door. Tricky thing with changing this o2 sensor is that the wires from it go up through the floor of the car and, while you don't have to remove the seat, you do need to get under the footwell carpet so lot of ripping of dash & trim to allow this. Other option is to cut the wires under the car going to the existing sensor and splice on the wires from the new sensor which means you have no messing inside the car but being honest, if you've the time, always better to do it right and just plug in the proper connector inside the car!
There is an excellent tutorial on the web (I'm sure it was on LOC) for replacing this sensor - I can't find it right now but I know I found it previously using google and it was step by step with photos and really helpful when I was doing mine.
Also, rockauto.com is the way to go for the sensor - Cheapest I could find at the time, Original Denso with correct wire length and plug, and delivered to the far side of the Atlantic in about 2 days B)
FINALLY FOUND IT B)
http://www.clublexus.com/forums/showthread...sor+replacement
All the info ya need!