JAIMECBR900

My car is running rich (based on my EGT reading). My CEL light is on, I haven't pulled the code yet but suspect that is a O2 sensor problem. My question is this: How come if this is going on, How did I pass my Emmissions test today with flying colors? Are my gauges wrong? Does one thing have to do with the other? I was actually thinking that I was going to fail and then when I changed the O2 sensor(s) I would have been at the required amount of $ that if I failed again it would be a mood point. Someone please advice.