We recently traded in the wifes 04 Is 300 195k miles & not one single problem with it. We bought her a 09 IS 250 with 39k miles. Had the car for one week & the check engine light comes on. So back to the dealership, its throwing the p0430. The dealership replaced the o2 sensor, bank 2. The car was fine after that for 6 days. Now the engine light is back on. It will be going back to the dealership again tomorrow Ive been doing some reasearch and Im guessing bad catalytic converter? What would cause the cat to go bad after only 39k miles? Im worried the dealership is going to just throw a new cat on & not fix what's causing the problem. We love the new car but we're almost thinking we should have just kept the Is 300 Thanks for any help I appreciate it!

 

Might be a dumb question but did they replace the correct O2 sensor? I recently got the same error code and a tech from Lexus recommended me to replace the O2 sensor first but told me it was the passenger side when it was the driver side. Before I bought an O2 sensor, I swapped mine around with the sides to narrow it down to either a bad O2 sensor or bad cats. If the same code shows up, it's the cat but if a new code shows up for Bank 1, then it's the O2 sensor. But after swapping them around, my CEL has never come on even after a few hundred miles which is strange.

The dealer with replace the cats under warranty. There's different causes but probably from what the last owner did. Maybe they pumped cheap gas and maybe not premium or other reasons.

 

Im not sure I hope, they replaced the right one, I'll check tomorrow. The diagnostic report they gave me says bank 2 sensor 1, and the work order paper work says the same.

 

It's suppose to be Bank 2 Sensor 2 though.

 

Well she took it back to the dealership today & they replaced he wrong sensor. Im still wondering why would a bad o2 sensor throw a p0430 code? Shouldnt it throw a code like p0156 bank 2 sensor 2 malfunction or p0157?

 

Are the two sensors identical and interchangable?

 

So we got a call from the dealership today. They've replaced both sensors on bank 2 & the code is still coming up. They are going to replace the cat tomorrow. I'm back to wondering what would cause a cat to go bad at 39k miles? Cheep or bad gas the only cause? If there is something causing the cat to go out I want to make sure they fix it, not just throw a new one in there.