I'm tellin myself it's gotta be the o2 sensor because I just got this converter installed. My mechanic thinks otherwise though, he's saying that the o2 sensors have their own separate code(s) and the car didn't show any others.
Get new o2 sensors before the cat since they're a lot cheaper and especially if you just got a new cat.
If there's a diy on egr and maf cleaning, post it in here pretty please and thank you.