A 1996 Dodge Ram 1500 w/5.2 engine. The front O2 sensor went bad, so I thought, "no problem. I've got the tools, I'll do it myself." Broke my sensor socket on it, 7/8" wrench won't budge it.
Little room to work at it as the sensor is in the caty convertor and points to the tranny pan and lower edge of the trans.
Went and got a new socket and saw an off-set sensor socket. Got 'em both. Went home, no budge. Heated the sensor nut (the sensor has broken off and out of the nut. Not in the way anymore.)
Got out the impact wrench and had to use a universal (swivel) for clearance and a 3/8 to 1/2 drive adaptor.
The nut still won't come loose. Had torch on the nut as my wife handed me the impact . Got it on the nut and put the power to it when the socket came off hitting me square on the bridge of the nose. So now I've tried everything I can think of, including breaking my nose, but it's nut is still in the convertor. I even soaked it in PB Blaster for a week before starting to get it out.
Anybody got any ideas?

I actually use a big open end wrench on mine.
not sure if it is better, but you don't get the slipage you get on a socket.

if you can get one in there that is. hard to envision what you described.

also, try to tighten it first instead of just loosening. see if it breaks something loose.

leave it in. get an oxy/acetylene torch and use it to open a new hole. don't blow the oxygen, just let it run and slowly open the hole. weld in a new bung, and call it done. bung costs a couple of bucks. your sanity and skin, will cost a lot more.

ok if you can u can cut the wires off the old sensor, u can also brake off the porselen part off to, the use a box end wrench.. but you may not have room, i use a sock for the O2, but if you can get that in there the make a o2 wrench with a flexible head.. also u can use a little heat, and then cold (freeze off) and that might help as well. trial and error

take your air chisel & hit it on the side of the nut in the direction to loosen it.

Heat it red hot.Then throw ice water on it.Ive rempved a few like that.The shock breaks the threads loose.I also use a good O2 socket or a SnapOn wrench when they wont come out.Rocky

Well we tried all of the above and more and it still wouldn't budge. Almost finished off my torn shoulder the Dr says needs surgery on.
Thought about it some more. Got my kid to come over & help. Since the sensor was already busted up and only the nut remained, we got creative. Put a 7/8" 1/2" drive socket on the breaker bar. He held the socket on the nut and I got out the floor jack. We put the floor jack saddle so it would hit the breaker bar enough to move it "slowly". A screeching sound came from the sensor nut and after repositioning the breaker bar a couple of times the nut came out easy.
Found out there is a different plug between upstream and downstream sensors. Dealer gave me 2 upstream, but swapped one out for the downstream.
Got it going now and sounding sweet behind the wheel again. Might even improve my MPG now. Anyway both sensors are new CE light is off. Seemed some better today on a couple of short drives.
Appreciate the help.

Glad to hear it's good to go. That CEL IS an annoyance, isn't it?!