I bought a Used 2004 S60 2.4T the last owner said the engine was replaced, and its throwing 2 codes a p0422 and a p0442. from what i understand P0442 is some sort of leak in the emissions system. The other P0422 Is a Main Catalyst Efficiency Below Threshold Bank 1. i did not drive the vehicle before these issues, but i feel the car is getting less then average gas millage (roughly 20MPG), and i feel the response on the vehicle is less then it should be. I have been reading different forms all the way from a failed catalytic converter, to leaks in the system, or faulty sensors.
keep in mind im getting horrible gas mileage and less then par response.
so if anyone can help on this it would be greatly appreciated.