Hey everyone
So ive been getting my SES light on and off from time to time. Sometimes it stays off for a maximum of about three months . The shortest its been off was about two days. The first code was PO430 , now I have P0430 and P0140.. i know those codes are for the oxygen sensors. I have a 2001 I30 with about 152000 miles on it. I don't think the original sensors were ever replaced. If I replace those specific o2 sensor, would that fix the problem? What are your experinces with this situation? Thanks!

Very rarely does the replacement of a rear O2 sensor "solve" a P0420/P0430 code.

P0140 is bank 1 rear O2 sensor (passenger side) while P0430 is bank 2 (driver's side). The two are likely unrelated.

It looks like there is a TSB related to your P0140 code - ITB02-027a - 2000 – 2002 I30/I35; MIL "ON" WITH REAR O2 SENSOR DTC P0138/P0139/P0140/P0158/P0159/P0160/P1147/P1167. If you choose to this TSB performed at the dealer, you'd probably have to pay quite a bit since both rear O2 sensors need to be replaced and the ECM needs to be reprogrammed.

If you'd rather try to simply replace the sensor, I believe this direct-fit Bosch O2 sensor is the correct part to solve your P0140 code. You can get it for $68.99 before tax if you order online with discount code CCABIN and pick-up in store. You'll need a 7/8" or 22mm (preferable) O2 sensor socket for replacement.

As for the cat, I'm not sure which bank is which since it appears that there's a front cat and rear cat on the same exhaust pipe. Check for air intake plumbing leaks and for exhaust leaks first before replacement, though.

Does your I30 burn any oil? Burning oil can hasten the demise of the catalytic converters.

Thanks! No my I30 doesn't burn oil.

Was getting those codes once
Tired of fighting them so changed all o2 sensors (never changed before)
Car had around 180K
didnt have problems then

yeah NutriaforBreakfast,I'm gonna change all four of them. tired of seeing thoose codes. Lol

how many sensors are there?