2004 Blazer - 1007K
I'm replacing my O2 sensors. The front 2 came out with now issues, but I can't seem to free up the post-cat sensor.

I've tried beating on the wrench with a hammer.
Heating the bung with a torch and wrapping JUST the sensor with a wet rag to cool and then beating on the wrench with a hammer.
Penetrating Oil for about 2 hours and then beating on the wrench with a hammer.
Since I'm replacing it, I considered cutting the wire and sticking a socket with an impact on it, but thought that might not be such a good idea.

My last thought was to take it to a shop and pay someone else to do it as I don't have a lift and a longer wrench with more leverage might help.

Any other ideas/suggestions?

 

I had one which was difficult like that too.

3 words for ya

Heat/pipe wrench

Those big red ones you know? Set that puppy on there and give it what you got. More pressure you put on it tighter it gets.

Worse comes to worse

You have a welder? Slice the section of pipe off,go to junkyard and get new section thats not eff'd up and replace. Or find a Nut that fits the sensor and make your own port on some pipe.