Hello, I recently bought a stock g37x sedan with 88k miles a couple months ago and I’ve been having cel issues. I hooked up the scanner to the car and got 2 codes, p0420 and p0430, so I reset it a couple times and got the code to come back when driving high speeds. I then took the car to the mechanic and he told me my catalytic converters had been hollowed out and welded. So I threw on 1 inch O2 spacers but the cel still hasn’t solved after around 50ish miles of city driving. So im wondering if it’ll be a big problem when it comes to driving, should I get High flow cats? (I still passed emissions when I first bought the car as I wasn’t having cel issues up until a week or two after)

 

Hello:

Personally, with your mileage I'd buy aftermarket full cats and then you're good. Autozone prices are all $200 or a bit below per, which means you could be on the road under $500 for the life of your car if you do it yourself.

High-flow cats can be insufficient to be legal (or in CA I think are straight illegal) and stand-offs illegal as well, and I prefer to avoid that. I run 200-cell cats in my street/track Cayman, and stock cats with aftermarket cat-back exhaust in my supercharged G37 Sedan, so 200-cell "high-flow" are not required for you at stock power levels, and potentially more expensive than a cheap aftermarket.

Good luck!


Rick