wP0421 Hyundai -where should I start?

Question

my car is running very rough. It acts like it has a cough, because it bogs out like it wants to die, especially when I accelerate from a stopped position. Also it seems like it's idling too fast, causing a lot of vibration. We just had the crank- positioning sencor replaced however, I don't know why or what caused that to go out either. My check engine light comes on sometimes. My code scanner spit out code P0421. please help, I'm just a girl, who don't know shit!

Answer 1

P0421 Warm up catalyst below threshold

Plugged exhaust system will do what you have described, There is also the rough idle condition that you have this would also set a catalytic convertor code, For now suspect a plugged exhaust system such as the catalytic convertor