Great another CEL! Now, I'm getting P0420, after replacing my bank 2 sensor 1 because of a p1150. I searched and read that it may be an exhaust leak, before the 02 sensor? Is that very likely? I hope so, those damn catalytic converters are expensive! lol

 

Hyper- is there a chance you have a crack in the exhaust manifold? They are known for cracking (they are stainless) and the crack can be pretty small and still cause the problem. I don't think you could necessarily even hear an exhaust leak. How thorough was the diagnosis and repair on the site you checked? There are quite a few other things that can cause a P0420.

 

I read about them on here.

 

I was getting a P0420 about 2 times a month.
I replaced that exhaust gasket that is before the cat. The one with the 2 bolts and springs.

That was about 3 months ago, and so far no CEL.

 

Thanks for that piece of info, I'm going to check that gasket soon. And, I'll let you guys know.

 

I could really hear mine leaking.
I think it failed because I had a broken-in-half flex pipe for a long time before that.-

 

Hypervish,

Were you able to find out what causes the p0420? I just got it and try to pin point where to start....

 

Ahh, yes. I forgot to update this thread.

I replaced the a/f sensor after the catalytic converter. It's the Denso 234-4215 Oxygen Sensor. After installing the new sensor, and resetting the light via OBDII reader, the light never returned, and still hasn't to this day.
Here's the DIY for it:https://www.clublexus.com/forums/rx-...sor-2-diy.html

 

Oh ok. So P0420 is directly related to faulty senor (after the catalytic converter)?

 

Usually it's just the sensor. < I researched as much as I could when I had this code pop up.
Another cause could be an exhaust leak. The last thing it could be is the catalytic converter (that's usually fine though).