Guys,
Instead of Liquid Wrench, try "PB Blaster" available everywhere ... even WalMart. I sprayed just a bit on my O2 sensor each day after work all week and by Saturday, it came out with just a tug on the socket (I borrowed an O2 socket from a buddy).

It took me a couple minutes to get it out ... and then I had to figure out the plastic clips.

--- Bror Jace