Trouble code P0420?
Thread Starter
Teching In
Joined: Jul 2004
Posts: 28
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From: Charleston, SC
Trouble code P0420? I just installed LT headers on my LS1 GTO and got the check engine light a couple days later. I do have a DS Predator Tuner and disabled it but what is this code..."P0420" O2's? What code(s) do I delete the O2's behind the headers?
Staging Lane
Joined: Apr 2005
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From: Homestead, Florida
Originally Posted by GerminaTOr
I just installed LT headers on my LS1 GTO and got the check engine light a couple days later. I do have a DS Predator Tuner and disabled it but what is this code..."P0420" O2's? What code(s) do I delete the O2's behind the headers?
Thread Starter
Teching In
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From: Charleston, SC
Originally Posted by renips
Cats are running below efficiency. LT's will cause this. Just delete and forget it. The 02 sensor is further down on the headers and it does not read right.
Staging Lane
Joined: Apr 2005
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From: Homestead, Florida
Originally Posted by GerminaTOr
I've deleted the t-code 2x now and am wondering if it's gonna just keep comming back? I looked at all the O2 sens that I could delete and here are the choices displayed on my tuner... P0137; P0138 & P0140; P0141; P0157 & P0158; or P0160 & P0161.
12 Second Club
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From: From Ohio now in that state up north
Yeah you will either need o2 sims or you will need to get some one with tuning softwear delete it for you or just live with the check engine light being on.
P0420? Stop hiding the ganja under the hood man! Sorry i had too.. 
But yeah sounds like you just need to find domeone that can turn those codes off for you and youll be fine. Most shops will turn off a couple codes fo ryou for dirt cheap. Dontw aste your $ on O2 sims, it can be better spent elsewhere.
Sorry i had too.. But yeah sounds like you just need to find domeone that can turn those codes off for you and youll be fine. Most shops will turn off a couple codes fo ryou for dirt cheap. Dontw aste your $ on O2 sims, it can be better spent elsewhere.
TECH Senior Member
Joined: Dec 2001
Posts: 5,399
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From: Jacksonville, FL
P0420 is a bank 1, post cat 02 code. Not familiar with the GTO predators, mine won't delete any permanently. I'd look up the codes and delete all the 02 post-cat codes it'll let you and see what happens. Maybe the way it's set up it'll delete the others too? Just a guess, but won't hurt to try.
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Verdad Gallardo Thread Starter
Teching In
Joined: Jul 2004
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From: Charleston, SC
Originally Posted by 2001NBMZ28
Just looked up the ones you listed, they're all post cat 02 codes.
Awsome...thanks! Yeah my tuner can turn them off too but I wasn't sure if I should just turn them all off or just a couple.BTW...where did you find that info?
TECH Senior Member
Joined: Dec 2001
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From: Jacksonville, FL
Thread Starter
Teching In
Joined: Jul 2004
Posts: 28
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From: Charleston, SC
Originally Posted by 2001NBMZ28
Sticky in the PCM forum 
www.ls1tech.com/forums/showthread.php?t=209783
www.ls1tech.com/forums/showthread.php?t=209783