well, this afternoon i went in to get my emissions inspection done. everything was fine until the guy got out and told me i failed it /forums/images/graemlins/mad.gif. i was just like WTF? he said too much nitrogen oxides. i dont get it, its a pretty much stock truck /forums/images/graemlins/confused.gif. it has an exhaust system, but ewverything is intact (or so i thought). anyway i have 30 days to get it fixed. he said it was most likely the cat or the o2 sensor. is either of these prone to failure? also, what do yall think itll cost to fix it?