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#4810070 - 07/10/18 10:40 AM P0430 code
wtd Offline


Registered: 06/25/02
Posts: 1956
Loc: southwest Mo.
Hi, I wanted to get some opinions from you guys on this code. This code popped up yesterday on my fiance's son's 97 GMC K1500 with the 5.7L. I hooked up my scanner and this is the code that was in it. This truck only has about 29,500 original miles on it. A couple of months ago, the distributor cap developed a crack and cylinders 2 & 8 were misfiring. The truck currently has a new distributor cap, rotor, plugs, wires, and a fuel filter.

Since the truck had been run quite a bit while misfiring trying to diagnose what the problem was and then ultimately driving it to a repair shop who discovered what the problem was, my opinion is that the excess fuel that was dumped into the exhaust from the misfiring has finally taken out the catalytic converter.

This code says this: P0430: Catalyst System Efficiency Below Threshold (Bank 2) The research I've done for this code suggests it could be several things that sets this code. One is a bad O2 sensor though there are no O2 sensor codes stored in the computer. Another is a leak in the exhaust system which I have looked and listened for that and don't see any signs of a leak, and lastly that the catalytic converter is bad.

While observing the live after cat O2 sensor readings on my scanner, the readings are switching back and forth pretty rapidly, just like the pre-cat O2 sensor readings which supposedly is another indication of a bad cat.

So for anyone here who has had this code come up on their vehicle, do you think a bad cat is causing this code? Are there any other tests that I can do before taking it somewhere for a cat replacement? Thanks for any ideas or info.

Wayne
_________________________
2014 Mustang GT
1998 Chevy K3500
1998 Chevy K1500
(2) 1992 Cavaliers
1970 Monte Carlo

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#4810079 - 07/10/18 10:46 AM Re: P0430 code [Re: wtd]
mehullica Offline


Registered: 08/19/09
Posts: 566
Loc: Modesto,CA
If the after cat O2 readings match the front O2 readings or look similar then the cat has become poisoned. Running with a dead misfire for any length of time can damage the cat.


Edited by mehullica (07/10/18 10:47 AM)

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#4810080 - 07/10/18 10:46 AM Re: P0430 code [Re: wtd]
Colt45ws Offline


Registered: 08/15/06
Posts: 9690
Loc: Central Washington
Yes. If you can pull up the rear O2 readings and compare them to the front, that is the best check.
If the rear O2 is switching at near the rate and amplitude of the front, the Cat is bad.
It should be switching at a much slower and a much lower amplitude.
I have yet to see a cat code (420/430) that is not a cat. The software is really good at figuring it out. Its really obvious if you look at the feedback from a good cat.
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#4810093 - 07/10/18 10:58 AM Re: P0430 code [Re: wtd]
wtd Offline


Registered: 06/25/02
Posts: 1956
Loc: southwest Mo.
Thanks for the information. I was leaning toward a bad cat but just wanted some other opinions before we have it replaced.
_________________________
2014 Mustang GT
1998 Chevy K3500
1998 Chevy K1500
(2) 1992 Cavaliers
1970 Monte Carlo

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#4810119 - 07/10/18 11:27 AM Re: P0430 code [Re: wtd]
wtd Offline


Registered: 06/25/02
Posts: 1956
Loc: southwest Mo.
Has anyone bought direct fit catalytic converters from discountcatalyticconverters.com?
_________________________
2014 Mustang GT
1998 Chevy K3500
1998 Chevy K1500
(2) 1992 Cavaliers
1970 Monte Carlo

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#4810189 - 07/10/18 12:11 PM Re: P0430 code [Re: wtd]
Rand Offline


Registered: 08/20/03
Posts: 12740
Loc: NE,Ohio
I'd do a battery disconnect to reset it

then try taking it on a long highway trip 100miles or so.. and see if the code comes back.

most aftermarket cats are junk most oem prohibitively expensive.
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#4810233 - 07/10/18 12:35 PM Re: P0430 code [Re: wtd]
NYEngineer Online   content


Registered: 12/12/06
Posts: 1621
Loc: NY, NY
I had a 98 Yukon that displayed that code after about 175,000 miles. I replaced the cats with Walker direct replacement cats. It worked out. My brother had that truck until about 225,000 miles.

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#4810236 - 07/10/18 12:36 PM Re: P0430 code [Re: wtd]
14Accent Offline


Registered: 08/03/17
Posts: 433
Loc: MN
Just make sure the aftermarket cats you get are C.A.R.B. compliant. They cost a little more, but are made MUCH better as they have to be certified for sale in California.

I agree most of the standard 49-state approved aftermarket cats are junk. There's a reason that they cost half or less of what an OEM/C.A.R.B. cat costs.
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#4810242 - 07/10/18 12:40 PM Re: P0430 code [Re: wtd]
MarkM66 Offline


Registered: 10/19/10
Posts: 1554
Loc: stl
Put an O2 spacer on it and forget it.

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#4810317 - 07/10/18 01:49 PM Re: P0430 code [Re: MarkM66]
maxdustington Offline


Registered: 01/21/17
Posts: 899
Loc: Toronna
Originally Posted By: MarkM66
Put an O2 spacer on it and forget it.

+1 You will be replacing those aftermarket cats too often to be worth it. Those cats are designed for end of life vehicles. New cat at 30000, yikes.

This is the same truck that got overreved in a mud field right?

EDIT: Put the money into replacing the spider injectors. 97+ GMT400's only flaw.


Edited by maxdustington (07/10/18 01:50 PM)
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#4810838 - 07/10/18 11:12 PM Re: P0430 code [Re: 14Accent]
Wolf359 Offline


Registered: 04/27/12
Posts: 4910
Loc: MA
Originally Posted By: 14Accent
Just make sure the aftermarket cats you get are C.A.R.B. compliant. They cost a little more, but are made MUCH better as they have to be certified for sale in California.

I agree most of the standard 49-state approved aftermarket cats are junk. There's a reason that they cost half or less of what an OEM/C.A.R.B. cat costs.


Well the reason is that they just have to last about 25k miles instead of factory ones which typically have to last at least 80k, I think some Pzev cars have to last 15/150k.

Rockauto also sells them, don't forget the 5% off code, may help with the shipping.

Also some say that the used cats may be worth close to $100 in scrap value.

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#4810847 - 07/10/18 11:22 PM Re: P0430 code [Re: maxdustington]
wtd Offline


Registered: 06/25/02
Posts: 1956
Loc: southwest Mo.
Originally Posted By: maxdustington
Originally Posted By: MarkM66
Put an O2 spacer on it and forget it.

+1 You will be replacing those aftermarket cats too often to be worth it. Those cats are designed for end of life vehicles. New cat at 30000, yikes.

This is the same truck that got overreved in a mud field right?

EDIT: Put the money into replacing the spider injectors. 97+ GMT400's only flaw.


Yes, this is the same truck that was overreved in the field. I personally have had good luck with aftermarket cats. I've put 150,000 miles on the aftermarket cat on my 92 cavalier and it still works fine. I've had an aftermarket cat on my 98 K3500 with the 7.4L for the past five years and it's still fine.

This is not my truck so I don't have the ultimate decision on how it's fixed. My fiance' wants it fixed and does not want the CEL to be on. She already has nixed the spider injector replacement from when we had the misfire situation. The truck runs fine other than the CEL is on.
_________________________
2014 Mustang GT
1998 Chevy K3500
1998 Chevy K1500
(2) 1992 Cavaliers
1970 Monte Carlo

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#4810850 - 07/10/18 11:25 PM Re: P0430 code [Re: wtd]
wtd Offline


Registered: 06/25/02
Posts: 1956
Loc: southwest Mo.
Thanks everyone for the input. She has not decided which route to go right now other than she wants the cat replaced.
_________________________
2014 Mustang GT
1998 Chevy K3500
1998 Chevy K1500
(2) 1992 Cavaliers
1970 Monte Carlo

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#4810865 - 07/11/18 12:14 AM Re: P0430 code [Re: wtd]
slacktide_bitog Online   content


Registered: 03/20/08
Posts: 6390
Loc: USA
Aftermarket cats are not a problem as long as you're not burning oil smile

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#4810969 - 07/11/18 07:17 AM Re: P0430 code [Re: 14Accent]
Trav Offline


Registered: 11/20/06
Posts: 19354
Loc: MA, Mittelfranken.de
Originally Posted By: 14Accent
Just make sure the aftermarket cats you get are C.A.R.B. compliant. They cost a little more, but are made MUCH better as they have to be certified for sale in California.

I agree most of the standard 49-state approved aftermarket cats are junk. There's a reason that they cost half or less of what an OEM/C.A.R.B. cat costs.


^ This is true.
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