I have 04 gs430 with like 142000 miles recently my check engine light came on for code p0420 i was wondering is there anything i should replace before getting a whole new catalytic converter

 

Exhaust leaks can also cause this code too especially around the flanges. I had this code due to a small exhaust leak in the past but I got rid of that code it with a $8 o2 sensor spacer which works if you do not have to do visual inspections for emissions because you will fail with that part installed.

 

Usually with P0420/P0430 check the exhaust leak first, then 02 sensor, and lastly your cat. I got the P0430 and it was an exhaust leak on my y-pipe. If you search you'll find a lot of threads where people replaced their cats only to have the code return.

 

hey shwalker, got a link to the o2 spacer? and do you put in on the downstream or upstream?

 

Here is the one I've used, this one requires you to drill the hole with a 1/2" drill bit on one spacer for your o2 sensor...

 

The thread size is M18X1.50 and you will see a lot on ebaymotors. I am running the stainless steel style ones with the 90 degree adapter on both of the rear o2 sensors after the catalytic converter. Never use these on your upstream sensors.

 

I have a code that is B2791 I'm not sure what this code means of possible

 

I have changed the 02 sensors on mine, but my 2003 gs VSC light and engine light are still on. Also Solenoid was an issue I guess ? mine has 142,000 miles as well

 

My 2017 lexus gives this error, i examined the error and p0420 code shows cat. converter problem, i ordered and was replaced the new one and code is gone...