So I picked up my civic last week and after 3 days of driving the check engine light came on. I took it to autozone to have the code read and it says it's either the o2 sensor or a bad catalytic converter. The day I got it I had it inspected my meineke so I took it back there and asked them what they thought it was. he said he thinks it's the catalytic converter, but I don't know why he is so set on that and not the o2 sensor. more money possibly? He didn't even look at it, and just told me its gonna be the cat. :-/ What are yall's thoughts on this? How do I check to see if my o2 sensor has gone bad?