ok so my inspection is up and my car just threw the code p0420 (BBCatalyst efficiency below threshold- bank 1). I brought it to an exhaust shop and they said i need to replace the drivers side cat and that it will cost around 275$. If im going to be spending that much money dont you think i should do something with a performance upgrade? What should i do and do you think thats really expensive to replace a stock cat?

 

Before you replace anything, make sure that the cat is the problem. P0420 can set because the cat is not working, or because of a problem with the O2 sensor. To check, swap the two after-cat O2 sensors side to side. If the problem follows the O2 sensor to the passenger side (P0430) its an O2 sensor problem. If the problem stays on the driver's side, its the cat or a wiring problem.

The driver's side cat is an odd shape, with a strange flange to connect it to the manifold. Its going to be expensive.... and the price quoted does not sound that unusual for the cat and the labor to install it.

You can look around for a high flow replacement, but then you will also have to upgrade the passenger side cat to a high flow model. That's going to run the cost up even more. The cats, as long as they are not plugged up, do not cost you a lot of HP.

You might want to add a "signature" with basic info about your car - year, model, engine, tranny and any major mods. That will help people answer your questions more accurately.

 

thanks alot man. I just added my signature. And im going to print this out and show my mechanic what you said about the o2 sensor. thanks again