Originally Posted by jasonlau8023
anybody know if i should replace both or 4 of o2 sensors?
i checked the price online, the price is killing me!!! around 160 each!!!
maybe i have to look for some used ones......
Don't buy used ones. And you only need to replace the after cat ones if the diagnostics indicate they are dead. I think you should go to a mechanic if you aren't familiar with cars.