When is it time to change O2's?

[lx mike]

Originally posted by mysweetlx
Will a bad O2 sensor cause any performance problems?

Yes they will. 02 sensors are in your exhaust pipe and they "sniff" the exhaust gas to see if your engine is running rich or lean. if they aren't working correct your fuel mixture can be off and keep you from passing emissions if they test where you are. also if your fuel mixture isn't correct then engine performance and gas mileage can suffer.