oxygen

removed the catalitic converter. it has a o2 sensor. i installed a straight pipe in its place. it has a o2 sensor before the catalytic also. is there some way i can wire the o2 sensor after the catalytic to the o2 sensor before the catalytic converter. the check engine light is on now i think...

I have a 2001 pontiac grand am and I have an oxygen sensor out. Now i understand that there are three oxygen sensors on the car. How do you know which one is bad? How much do they generally cost? and how do you change them?

or gravity?

I have a Hyundai Elantra and I would like to know if anyone knows a website or any information on how to replace the O2 sensor. I wouldn't want to take it to a garage because it would be way too expensive. The part itself is expensive so I wouldn't want to spend anymore. Any ideas?

THanks