I have an 03 Z. Recently I had a code thrown for bank 2, sensor 2 o2 sensor. I also noticed around this time that my car started to sound a little different. Almost raspy. It also started to puff out some nice clouds of black smoke. It has always burned oil, but the smoke is definitely black now and not just blue, it also smells like fireworks, which makes me want to say its almost a carbon smell. I replaced the sensor yesterday and cleared the code and it was good up until my way home tonight. I've cleared it before and its always came back on. When I was driving home I got on it pretty good, hitting about 7k RPM's and the light came back on. Cleared the code again and it was good for a couple miles then came back on. My question is this: Could I possibly have "bad" or clogged cats that are falling apart and fouling the sensor? Could the oil burning itself foul the sensor? Is there a chance the sensor was never really bad and it was something else throwing the code? Any input would be appreciated.

 

If what you're smelling reminds you of Sulfur, and you're getting a bank 2 sensor 2 O2 code, it means your bank 2 cat is kaput and needs replacement. This will throw off your air/fuel mixture, and all sorts of goodness is going to come out of that tail pipe.

 

An exhaust leak will throw the code.

 

Should I just get oem cats and replace them or buy some universal high flow cats and get them welded in?

 

That's going to be your call. I had both of my cats replaced under warranty before my car even reached 25,000 miles after getting those sensor 2 codes on both banks. Nothing but Chevron Premium went into the tanks and the car's been maintained religiously (it's only got 37,000 miles on it now).

If you have any doubts about it being the cat, you might want to have it scanned on a CONSULT computer at Nissan just to make sure. For me, I just drove the car in, they plugged it into the computer and 3 minutes later, they came out saying, "you need a new cat." Both times. They wouldn't venture to guess why both cats crapped out with so few miles on them, but they did tell me that bad cats are NOT uncommon on the 350Z.

There are tons on threads on hi-flow cats.

 

Oddly enough my check engine light went off yesterday. It has the old O2 sensor in it still but it went off on its own. I'm going to plug it back into the scan tool just to make sure for some reason the bulb didn't go out in the dash or something but my car seemed to fix itself 🤔