I have the dreaded P0430 code, which says it's the passenger side cat under-performing. It's a 2012 G37S convertible 6MT with 150k. The car has a basic cold air intake but is otherwise all stock. I've so far replaced spark plugs, replaced fuel cap, and run the car up to normal temps several times after clearing the code, but the code keeps coming back.

I have a few questions:

• Should I bother with replacing the right rear O2 sensor first?
• There's no way I'm buying an OEM cat. I'll probably get one of the options Z1 motorsports recommends, like the Kinetix or Fast Intentions cats. The rest of the exhaust I plan to leave as stock for now...no cat-backs yet. Which one would be best for not getting too raspy while giving the least restriction without a CEL coming back?
• I'm assuming the cold air intake and the new HFCs affects the defaults the ECU has for exhaust pressure and the amount of air the engine would otherwise get with the stock air filters to the degree where the ECU would not take full advantage. Will I need to get a tune to keep the CEL from coming back afterwards? If not, more broadly speaking, I wonder if getting a tune is worth it with the basics like cold air intake and HFCs if I'm not yet going crazy with forced induction.

 

For the cat code try cleaning it. I used all 3. I use this oil also. Had codes for both cats. I have the cheap $100 ones from eBay. Had oil leaks that were contaminating the cats. Fixed the leaks then cleaned. Been code free for months.

Motul 8100 X-Clean EFE 5W30

https://www.walmart.com/ip/Chevron-T...hoCcu8QAvD_BwE


https://shop.advanceautoparts.com/p/...BoChigQAvD_BwE

 

This was for my Jeep, but you should be able to check for the same. I hooked up an OBD reader and read the O2 sensors. The rear sensor should be fairly constant. If it's bouncing around, it might be bad.

 

I love Scotty Kilmer! I don't know if I'm brave enough to add half a tank of lacquer thinner to my engine though.

I just used a bottle of cataclean in the engine and cleared the code. Fingers crossed it won't come back!

@pinecone good call on watching the O2 sensors via scan tool. I have a cheap one but the app I use (Tor OBD2 on Android) doesn't seem to show results other than aggregate results but I will see if I can get a more granular reading.