JASON.BLAKE1
Member
hi i have a 2001 protege mp3 with a 2.0 it has been running pure and the cel is on. went to auto zone and got codes p0421 and p0300 421 is catalyst 300 is a misfire first can the 421 be causing the 300 and also most of what i read says its probly the cat but could also be the o2 sensor. any way to check so im not just throughing parts at it. any help would be awsome thank you