My o2 sensor bolts were rusted so bad a socket nor vise grips would get them off, so i took a file and filed 2 opposite sides of the nuts down close to the stud bolts and then took vise grips and removed them after a shot of pb blaster I figured the sensor would have looked worse but mainly was just black carbon on it (wasn't kicking any codes) but I have never replaced it in the 6 years i have owned it so i figured it couldn't hurt anything. BTW i found a couple good pics of the sensor online.






highway

 

Get some of these, they work.