Hi, I have a 2007 s40, and recently, when i press the gas pedal hard, like almost full gas, the check engine light comes on, we read it and it gave the p0420 error. is this due to a faulty cat? or is it because it is dirty, and i maybe can fix this with fuel additives?

i am sorry, i don't know a lot about cars, but because i could not find any help about this exact problem, i am asking on the forum.

 

No its either a faulty sensor or a leak in the exhaust system that is what p0420 is