01 GS300 Oxygen Sensor problem

[Dan A]

My 01 GS300 w/33000 miles showing code 0161 (Heated Oxygen Sensor Circuit Sensor 2 Bank2). Any ideas? Seems too few miles to replace sensor. How many are there 2, 3,4? At first look, I saw two under the hood. Are there more in the exhaust line? Would cleaning them be a possible solution? I priced them out at auto parts store and they range from $75 tp $250 each. Checked with Lexus dealer and he said it's NOT covered under emmisions warranty. My regular four year warranty is over so any repairs are out of pocket.

Any help would be appreciated.

[Dan A]

Further information. Learned through one the Lexus dealer's technicians that even though I have 33000 miles, it's usually the sensor gone bad. It's a time thing rather that mileage. It's the sensor behind the cat converter. Doesn't affect the engine performance but monitors the cat converter. You have to remove the passenger seat to get at the cable connection in order to remove it.

Has anyone had experience replacing one? Would appreciate any tips. Do I need a special o2 removal tool?

Thanks