beaterman

Well I just bought this car and on my way home it threw an o2 sensor code. I had the nice people of autozone reset it for me and I failed inspection since sensors were "not ready" well today driving to work the engine light came back on. I'm sure its the o2 sensor again. If this is the case would a gutted cat be making the o2 sensor going off? I only believe its the cat because of the amount of carbon coming out of the exhaust. What do you guys think?