Oxygen Sensors...

If a car has two oxygen sensors which one could cause it to misfire? After or before the catalytic converter? How do I know which one is before or after? (before cat is closest to the engine?)

Thanks

I'm assuming you have a check engine light on and codes for a misfire and oxygen sensor. A bad oxygen sensor won't cause a misfire, but a misfire will cause an oxygen sensor code and can cause oxygen sensors to go bad and catalytic converters to clog if the misfire isn't taken care of soon enough.