P0430 possibly caused by section of flex pipe ?

[A97obs]

POST EDIT: Missing cat issue resolved !!
Credit to east302



So I have edited this post heavily after I have figured out what a factory 99” 5.7L CA emissions c1500 suburban exhaust and Cat converter illustration should look like.

I bought this truck out of CA Recently and immediately realized they sectioned in 12” flex pipe in the down pipe driver side below floor pan before the curve where the o2 bung would be.

I can’t imagine why the need to flex pipe that area there’s no cat no need to unless it was damaged/bent restricting flow . Never had a sel come on at all for exhaust issue until yesterday with a p0430

I can’t see that code being a bank 1 issue because it’s supposed to be related to a bank 2 cat or sensor issue so I assume the flex pipe sectioned in on thr bank 1 down pipe
((Driver Side)) could not be to blame for a P0430

Any ideas ?

 

[Pinger]

You are creating confusion - in my mind at least - referring to a Y-pipe. Y-pipes AFAIK are for single cat systems where two pipes merge into one. The pipe you have that has been altered I'd just call a down pipe.
FWIW, my 99 C2500 Suburban's system is pretty much as per the two photos in your post. I think, exhausts vary between 1500 and 2500 models. Others will know more.

 

[A97obs]

You are creating confusion - in my mind at least - referring to a Y-pipe. Y-pipes AFAIK are for single cat systems where two pipes merge into one. The pipe you have that has been altered I'd just call a down pipe.
FWIW, my 99 C2500 Suburban's system is pretty much as per the two photos in your post. I think, exhausts vary between 1500 and 2500 models. Others will know more.

POST EDITED:
My fault Ill refer to it as a down pipe then I was confused as it still crosses over like a Y shape just not welded into one single outlet like I’m used to dealing with .

Yes that’s how I see the way mine looks also , but I keep getting denied exhaust work because the shops think a cat is missing since I have a sectioned piece of flex pipe from previous owner . Which makes zero sense as to why it’s there unless a cat was missing or it was heavily damaged /bent and was possibly restricting flow or a 99” model year had a diff cat or 3rd cat placement

 

[east302]

This is what the parts diagrams show for an L31 1500 Suburban with California emissions (RPO code NC1). Not sure if you have that but maybe it’ll help?

My trucks (like @Pinger) match your Rockauto photos and are not California emission. Best guess is that you’re missing a converter and the wiring is tucked up in there somewhere.

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Regular Federal Emissions L31 1500 Suburban is below…

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[1998_K1500_Sub]

@east302, good sleuthing.

From the image I'm guessing CA standards were more easily met if the cats heated up faster, so GM put them closer to the engine.

 

[618 Syndicate]

So I have edited this post heavily after I have figured out what a factory 99” 5.7L CA emissions c1500 suburban exhaust and Cat converter illustration should look like.

I bought this truck out of CA Recently and immediately realized they sectioned in 12” flex pipe in the down pipe driver side below floor pan before the curve where the o2 bung would be.



Any ideas ?

Is the O2 sensor there?

 

[A97obs]

Yes the o2 is indeed wired and installed on both upstream banks

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[A97obs]

It was just a mystery talking to some people and Jegs bringing up Y-pipe / illustrations for a 99 ca emissions truck options they also stated from what they seen there would be No cat on the driver side down pipe.
So it’s Just ends up being an odd ball scenario being a ca truck and a 99 last year model possibly .

 

[A97obs]

This is what the parts diagrams show for an L31 1500 Suburban with California emissions (RPO code NC1). Not sure if you have that but maybe it’ll help?

My trucks (like @Pinger) match your Rockauto photos and are not California emission. Best guess is that you’re missing a converter and the wiring is tucked up in there somewhere.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

Regular Federal Emissions L31 1500 Suburban is below…

You must be registered for see images attach

Excellent find …. thanks now I know I need to weld up a cat!

 

[Pinger]

Mystery solved by the looks - but for where the missing cat is. Stolen?