Car was smelling like sulfure badly, i changed the main cat, car still smells, but not as much, should i change the precat also, i have code P0420 ( three way catlysts(manifold)). So is the precat now that need to be changed to reduce the smell ?

 

if the cat is new, you should smell something when you break it in. does it still smell after a while?

about the P0420....have you confirmed the cause of it is not the pre-cat failure? there's a TSB for this and sometimes this code is triggered by incorrect ECU programming. you can try to confirm it by disconnect the negative battery cord to erase the code. If it comes back once you start the car, it maybe the precat. if not, it might be the problem described in the TSB.


good luck.