I'm sure this has been asked before and i apologize, i am just in need of a quick response. My 2002 Wrx is throwing the P0420 Catalyst efficiency code. I have been told that it is most likely the rear o2 sensor. I called my local autoparts store and they have one but it needs to be ordered and its 87 dollars but they also have a 50 dollar universal fit o2 sensor. My question, will i be okay using this o2 sensor? I know its not OEM and i am also not sure who manufactures it, but will i be okay to go ahead and purchase this sensor and then buy an OEM one alittle later on?