where is the oxygen sensor located on a 1998 honda accord LX. 2.3L 4cylinder? how do you change it? what kind should i buy?

 

There are 2.

One is right on the exhaust manifold (near that metal cover that says hot) and one is behind the catalytic converter under the car.
They un-screw from the piping. There is a special socket for o2 sensors that makes taking them out a snap. It's not too hard to replace them. I would try to stick with OEM honda parts if you could.