I am going to replace, either myself or my mechanic, the o2 sensors on my wife's 2001 KIA Sportage. I wanted to save some money and order the parts online, however when I pull up parts from eBay or AutoZone they only give one type (part number). I know there are 2 sensors, one before the catalytic converter and one after. I just wanted to see if anyone out there knew if these two parts are supposed to be the same thing?