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Discussion Starter #1
Hi guys,

I got a SES light today and had it diagnosed by Autozone and they pulled a P0420 code which says Catalyst System Efficiency Below Threshold Bank 1 . It has to do with my exhaust flowing too freely for the cats and my computer is throwing a code. My question is will this cause a drop in performance?
 

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Sir Clavin
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Yep! Basically, your computer sees that the catalysts are not doing there job properly and will try to compensate to reduce emissions. Ask the LS1 guys, I know that some of those have problems throwing codes when mods are installed.
 

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Discussion Starter #3
[CS]ls1haha said:
Yep! Basically, your computer sees that the catalysts are not doing there job properly and will try to compensate to reduce emissions. Ask the LS1 guys, I know that some of those have problems throwing codes when mods are installed.
Damn, I might have to put my baby down:(
 

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Discussion Starter #5
lowthreeohz said:
all the weed smoking threads on here lately and nobody else thought that was funny?
What:confused: Are you going to contribute to my P0420 thread?
 

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Erfan Z28 said:
Hi guys,

I got a SES light today and had it diagnosed by Autozone and they pulled a P0420 code which says Catalyst System Efficiency Below Threshold Bank 1 . It has to do with my exhaust flowing too freely for the cats and my computer is throwing a code. My question is will this cause a drop in performance?
Flowing too freely for the cats? You dumped it at right off the damn ports. How abut not flowing through the cats at all.
 

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Discussion Starter #7
Re: Re: Does a P0420 code affect performance?

Swoll5.0 said:
Flowing too freely for the cats? You dumped it at right off the damn ports. How abut not flowing through the cats at all.
Here is the setup:

Manifold then pipe with cat on it and then pipe after manifold to driver side door, and the same for the other side. So the cats are still there and it is dumped after the cats.
 

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just like on your gt when you had to get mils, they make the same thing for the ls1's, you need to get those.
 

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Discussion Starter #10
DarkPony said:
just like on your gt when you had to get mils, they make the same thing for the ls1's, you need to get those.
I might have too, they have o2 simms for them. They're $95:eek:
 
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