cat heat shield

my heat shield is ratting like a bitch through 3k and 5k rpms. i tried to take it off but couldnt get the 02 senser disconected. any one got any tips? and will my check engine light go on if i take the o2 senser off and put it back on?

Not as long as you don't damage the sensor. I personaly just use a wrench and take the O2 sensor out with that, but there is also a socket that is made just for O2 sensors.