How to get a stuck O2 sensor off

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

1. 1
   Using penetrant oil
2. 2
   Cutting the wire and using a 6-point deep socket
3. 3
   Applying heat with a torch
4. 4
   Running the engine up to operating temperature to add heat
5. 5
   Having an exhaust shop weld a new bung to the pipe
6. 6
   burning it out using acetylene and oxygen torches
7. 7
   using a pick and pliers to pry out the remaining pieces and O-ring
8. 8
   Take it to a mechanic shop
9. 9
   Weld a new bung onto the pipe

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.