Brought my IS350 to autozone with check engine light on and got code P0430. Description is Catalyst Efficiency Below Normal (Bank 2). Does anybody have experience with this issue? Any DIY fixes and advice on what to do? I need to fix it because I wont pass emissions with it broken.
Thanks for the help!

 

Any mods? (10char)

 

I assume the CEL stays on after shutting off the car? Have you tried disconnecting the battery for 20 minutes for a full system reset?

 

P0420/P0430 codes are usually not the result of a bad 02 sensor, but rather a crack in the pipe near the sensor which allows excess oxygen into the exhaust stream. I would bring your car to a good exhaust shop and have them find and weld the crack shut. I had them do that for my IS350 for $20 bucks, code has been gone since!

 

Synrgy350 is correct that an exhaust leak is the most frequent cause of P0420/P0430 codes in the Lexus IS.

Usually small holes form in the mid pipe under the heat shield.

The code isn't caused by excess oxygen, but rather due to the fact that hot exhaust gases are leaking out, increasing the amount of time it takes for catalyst light off. The catalyst efficiency test is performed very early in the drive cycle, so it is hit-or-miss whether the test is performed before or after converter lightoff. That's why at the beginning of this problem, people find that the check engine light goes off by itself after a few days, only to return a short time later.

 

It's a cracked y-assemble or pipe assembly of that nature. Same happened to me a month ago. Got it fixed for free while out of warranty. I would advise you go check it out and see what they offer you.

 

I installed an exhaust about 2 years ago and f sport intake. Those are the only mods. I'll check for cracks today and see what I can find. Where would the most common leaks be located?

 

Under the heat shield in the Y pipe.

 

I too had the P0420 code. I ended up having to replace the bank 2 cat. No light since, good luck hope you can avoid having to do what I did.

 

how much did that run you if I might ask; $2k (at the lexus dealership)?