My o2 sensor was gone so i bought a new one and now i can't get the old one off. Tried combo wrench, tried socket wrench and i even tried a heavy duty impact wrench, and the sob won't give. Any suggestions? Can the car run for a while with out it?

 

Have you soked it in PB blaster? That stuff is a amzing and should soak into the threads enough to allow you to break it loose. You may also want to try to heat it up. I would soak and soakl and soak it in PB blaster hours before your next attempt. Your car will run without it but it will hate you for it.