yeah like i said its easier to wait till the manifold is out of the car to get the o2 sensor off because its very hard to get out you may wanna just spray it with liquid wrench wd-40 or some other form of penetrating oil and let it sit for awhile then find the largest longest wrench you can find that will fit on there cause chances are yuore gonna need all the leverage you can get. And its threaded normally so if youre struggling with it and it isnt coming out DO NOT think that it is reverse threaded because it IS NOT!
Robster