too bad, I was hoping for an easy fix.
NEVER ever work under the car when it is jacked up unless you are positive it can't fall on you
I've replaced the one after the cat, I disconnected the connector inside the car (on the left side of the front passenger footwell)
then pulled the rubber grommet and wire through the floor, and threaded a box end wrench over the wire to get to the sensor. Looking at an old thread I used a 7/8" box wrench, that's pretty close to 22mm.
If I remember right, it took some force to get it started
I've never tried the one on the exhaust manifold, I expect the main difference would be physical access to the thing