This is possibly a dumb question asked a year and a half too late, based on the thread date. What is the bung? If you are heating up the sensor base, that should make it harder to get out because it would expand. If that is the metal (steel or iron) that the sensor screws into, that makes...
Do you mean to break it off so you can put a regular socket on it, or do you use the chisel at the base of the sensor to shake it loose enough to turn?