P0420/P0430 OBD code - what a bad catalytic converter looks like
 

No question, just thought I'd share a little info that might help others with codes P0420/P0430. Often I see people asking if the O2 sensors are bad or the catalytic converter. Since I use the ScanTool and software to graph the O2 sensor voltage levels, I think it's safe to see, in my case, that the bank 2 (right side) catalytic converter is toast.

Bad cat Bank 2 (right/passenger side) - notice the signals are nearly the same both pre (sensor 1) and post-cat (sensor 2), meaning, the cat isn't doing anything.

https://chevroletforum.com/forum/mem...erter-7921.jpg

Good cat (bank 1 left/drivers side) - The pre/post cat signals are very different.

https://chevroletforum.com/forum/mem...d-cat-7920.jpg

If I'm wrong, please let me know and I'll correct this post. I would hate to have a reference with bad information.

I'm using the OBD Wiz software
ScanTool.net LLC - OBDwiz Automotive Diagnostic Software

that came with my cheapo OBD interface.
OBDLink SX Scan Tool USB Interface w/ OBDwiz Diagnostic Software

on my little Gateway notebook. Well worth the $49!

That is nice info to see...:cool:

What version of the software are you using?

You are correct. If upstream and downstream voltages mirror each other the cat is not working thus po420 or po430

2.15.1.738 Think they can add a few more numbers? :D

My bad, are you using the one that comes with the OBDLink SX Scan Tool, the Scan XL standard or the Pro....

Correct, it came with the SX. Actually, I think the version that came with it was older and I downloaded the latest version at

http://www.obdsoftware.net/obdwiz.aspx

Code p0420 and p0404 just swapped in a new cat, no more codes

thanks for the follow up! :cool:

FYI - Just had to replace my catalytic converter, vent valve, sub harness and O2 sensory on my 2007 Suburban with 84k miles...a $1,230 job. I missed the gov emissions warranty by 4k miles.

Will these codes cause the reduced engine power messages? I just had my throttle position sensor replaced and I am still getting this code....supposedly they cleaned the throttle body while replacing the sensor.