My car had three codes P0420 catalyst efficeny below threshold, P050A which from what i can find meant it had a bad cold startup and P0302 which is a misfire i brought it to the dealer and they said it was a bad catalytic converter? Which is fine if it is because its under warranty but how can the catalytic converter go so quickly car is all stock except for an K&n intake and is a 2007 with 17k miles could the K&N intake have made it go or are they wrong and something else is wrong?

 

Cat can go bad. Don't worry about it just let them install a new one for you.
Don't let the dealer say that the intake had anything to do with it. Because it didn't.

 

The cat going bad is something that can happen on the 8, like Easy said. Don't let the dealership try to blame anything else on the cat going bad... it should be replaced under warranty no ifs ands or buts.

 

If you can, try to get them to give you the old cat as well ...

... then you can get the platinum out of it and keep it for the future.

 

they will be doing it regardless under warranty but im just wondering if the intake could of caused it and if i should take the intake off of the car and put the stock box back in with a K&N drop in? do love the sound of my intake thooo

 

No, intake would have nothing to do with the cat failing. Keep your intake - there are no benefits to putting your stock air box back in (unless you go in to get warranty work done again and don't want to be hassled)

 

Yes but won't you sometimes get the catyltic converter code if one of the o2 sensors is bad and isn't it possible that my intake could ruin the o2 sensors?

 

Not really... I mean, the sensors are the same unless someone changed them out with the new intake... Also, I guess the intake could be poorly designed and the O2 sensors aren't reading what they're supposed to be which is causing the car to run rich which is causing the cat to get clogged up.

But the intake is just an air duct, the better the intake, the less the engine works to pull the air through the filter and bring it into the engine... I could be speaking out of turn, but I don't see how an intake could lead to failing O2 sensors.