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

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

Old September 8th, 2013, 12:35 AM
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Default 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.



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



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!

Last edited by CableSux; September 8th, 2013 at 12:37 AM.
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Old September 8th, 2013, 9:41 AM
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That is nice info to see...

What version of the software are you using?

Last edited by in2pro; September 8th, 2013 at 9:46 AM.
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Old September 8th, 2013, 12:28 PM
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You are correct. If upstream and downstream voltages mirror each other the cat is not working thus po420 or po430
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Old September 8th, 2013, 1:45 PM
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Originally Posted by in2pro View Post
That is nice info to see...

What version of the software are you using?
2.15.1.738 Think they can add a few more numbers?
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Old September 8th, 2013, 2:27 PM
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My bad, are you using the one that comes with the OBDLink SX Scan Tool, the Scan XL standard or the Pro....
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Old September 8th, 2013, 11:21 PM
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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

Last edited by CableSux; September 8th, 2013 at 11:24 PM.
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Old September 9th, 2013, 4:21 PM
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Code p0420 and p0404 just swapped in a new cat, no more codes
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Old September 9th, 2013, 4:40 PM
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thanks for the follow up!
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Old September 18th, 2013, 9:05 AM
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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.
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Old May 20th, 2016, 2:07 PM
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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.
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