I replaced the cats in my 2008 350Z but am now getting P0420 & P0430 codes

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Mar 26, 2018 | 01:42 PM

cyn4747

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From: Tampa

I replaced the cats in my 2008 350Z but am now getting P0420 & P0430 codes

I just replaced both cats in my 2008 350Z convertible. Next day CEL is on again with codes P0420 & P0430. My mechanic says its the O2 sensors that need replaced now. I need to buy the parts for him to replace. Opinions on whether the diagnosis is right? How many sensors does it have - 4? Recommended brand of sensor? Thanks for your help -

Mar 26, 2018 | 02:03 PM

karlt

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From: Williamsville, NY

I suggest you download the ec.pdf section of the service manual for your car and read up on those faults. Bad O2 sensors may not be the problem. You can find the service manual here:
http://nicoclub.com/archives/use-nic...-database.html

Mar 26, 2018 | 02:51 PM

zakmartin

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From: Seattle, WA

All the 350Z manuals can be downloaded from here (new link):

http://nicoclub.com/archives/nissan-...e-manuals.html

Edit:
OP, did the mechanic replace the cats with OE parts or aftermarket? Did he test each O2 sensor or does he prescribe you just throw them all out and start fresh? If it's the later, you need a better mechanic.

Last edited by zakmartin; Mar 26, 2018 at 02:54 PM.

Mar 27, 2018 | 06:29 AM

cyn4747

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From: Tampa

P0420 & P0430 error

The cats are aftermarket. I have to buy the parts because none of the mechanics I have supply parts. I bought Eastern Cat ECO 3 converters for both sides. The CEL came on again the day after I picked it up. When I took it back they read the codes again and told me it was the P042 & P043. When I asked him if it might be the O2 sensors he said probably. The first time the CEL came on was in December. I had two different mechanics check the code and they both said it was a bad cat so that was why I replaced those first. Now I’m not sure what to try next because I thought that would fix it. This is my second Z car. Never had any issues with the first one but this one has been a headache.

Side note- the car has 98K miles on it.

Thank you again for your help.

Mar 27, 2018 | 07:42 AM

jhc

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From: ZdayZ

Your new sensors may or may not be the problem. For $6 you can get spark plug No-Foul adapters for the downstream O2s. Each O2 will require 2 adapters and a little drilling. This tricks the ecu into thinking everything is good.
Search for no foul on O2s. Gl.