Wondering if anyone has any hints here. 1997 F150, V6, 4.2L. Replacing the O2 sensor, driver’s side before the converter. I’ve tried using the O2 sensor socket (I have a full set) and it keeps slipping off. Afraid I’ll “round” the sensor even more. I’ve tried heating it up, penetrating oil and it’s not budging at all. Anyone have any ideas ?
There’s probably not room to get an impact in there? There’s no need to be gentle on the wires in terms of removal if its on its way out. Cut them off, put a regular, probably deep, 6-point socket on it. If you can’t fit an impact in the space I’ve always had a lot of success with the “poor man’s” impact - the regular ratchet on the socket - give the end of the socket handle some sharp whacks with a hammer (in the correct direction, of course).
What are you using for penetrating oil? A lot of people think WD-40 - I like PB Blaster. Others speak highly of SeaFoam’s Deep Creep.
Ford built it, let them change it…
Note: Special Tools, Extra Effort or Destructive Force may be needed…
F150’s are easy. Try changing the forward sensors on a Crown Vic…
Hey - I thought you never had to fix a Crown Vic - don’t you just drive 'em ? 
Just cut the wires off of it, break the porcelain off, and use a boxed end wrench on it.
I’ve got several O2 sockets and personally, I can’t stand the things.
When reinstalling a new O2 do NOT drop it, bang it into anything, or overtighten it. Overtightening can stress the sensor and it’s always possible to damage a circuit in there.
Snug is good enough, just like spark plugs.
If you have room, a pipe wrench will do it, or a pipe wrench with a piece of pipe on it.
Break the old sensor apart so you just have the “nut” part of it left and use a shallow six point socket and a breaker bar to loosen it. Once it’s loose, use penetrating oil and go back and forth on it, loosening it and tightening it, and gradually loosen it more until it’s out. Sometimes when they’ve been in there a long time they will require a substantial amount of force to remove.
Instead of using the special sensor socket, which has an open side for the wire, try using a normal long socket, like one for a spark plug. Cut the wire off the sensor to make room to use a normal socket. Even better, make sure you get a socket with 6 sides, not 12.
Have you tried disconnecting the wire and putting a wrench on the sensor?