is3501999

Hi I recently got a used 2008 IS350 with 100,000 miles on it. I just got a check engine light and a check vsc light and scanned the computer for codes. The only code in the system is p0430. The original owner drilled an f sport inspired hole into the air box and installed a k&n filter just fyi. I checked my o2 sensor readings and my fuel trims as well at idle. The upstream o2 sensors are both behaving normal and seem to average about 3.2 volts. however the downstream sensors read different. bank 1 sensor 2 reads around 0.7 to 0.8 while bank 2 sensor 2 reads 0.095 to 0.075. My short term fuel trims match decently but both read -2 to 0 at idle. The long term fuel trims differ long term trim 1 reading -4.5 to -5.5 while long term trim 2 reads a steady 2.3 at idle. I heard a dirty MAF sensor can cause negative fuel trims at idle but the issue persists after cleaned the sensor. Im wondering what could be causing this. If anyone could give me some knowledge here that would be awesome. The data makes me suspect that my bank 2 catalytic converter has a leak in it. I just want to make sure the data doesn't point toward an o2 sensor being bad or a different issue due to me interpreting it incorrectly before i spend 1000 on a new cat.

4mula_J87

Did you get the cat looked at... try cleaning it first that’s what I did.

AMIRZA786

I'm pretty sure the K&N filter is not related to the issue. I have been running these in all my cars for over 10 years (two of them over 100K on the same filter, cleaned once of course). I can't speak for the drilled hole in the airbox. Personally I would've just put in an aftermarket airbox, then before selling the car to someone else, restoring it back to stock instead of modifying the stock intake

cyphur

you may have a leak somewhere.
I have been dealing with that for about 3 years. I would just reset to the computer to reset the codes and finally got fed up and bought a code scanner late last year. I finally jacked to car up to see if I can see anything (I could hear a flutter with the windows down).
But there was a leak under the heat shield drivers side. Once removed...Went to advanced auto and got some QuickSteel and exhaust wrap.
I went from getting the code once every couple of weeks to once every couple of months as there is still another leak somewhere higher up closer to the headers but I do not have the skills or tools to get in the tight space.

is3501999

i have not gotten the cat looked at because i want to avoid spending more money at this time. thank you for those pictures i appreciate all your replies. Im thinking i may say screw it and just get a full exhaust and headers and a tune since a new exhaust manifold is so pricey. what all does replacing the exhaust manifold entail? Does the engine need to be jacked up?