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P0430 code #4810070
07/10/18 10:40 AM
07/10/18 10:40 AM
Joined: Jun 2002
Posts: 2,122
southwest Mo.
wtd Offline OP
wtd  Offline OP

Joined: Jun 2002
Posts: 2,122
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
Re: P0430 code [Re: wtd] #4810079
07/10/18 10:46 AM
07/10/18 10:46 AM
Joined: Aug 2009
Posts: 592
Modesto,CA
mehullica Offline
mehullica  Offline

Joined: Aug 2009
Posts: 592
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.

Last edited by mehullica; 07/10/18 10:47 AM.
Re: P0430 code [Re: wtd] #4810080
07/10/18 10:46 AM
07/10/18 10:46 AM
Joined: Aug 2006
Posts: 9,991
Central Washington
Colt45ws Offline
Colt45ws  Offline

Joined: Aug 2006
Posts: 9,991
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.


-Colton
2002 Ford Crown Vic PI 207k, Ex-Kootenai County, ID Unit #42
Down for engine swap
2003 Ford Crown Vic PI 86k
Pennzoil Conv HM 5W30, Fram XG2
Re: P0430 code [Re: wtd] #4810093
07/10/18 10:58 AM
07/10/18 10:58 AM
Joined: Jun 2002
Posts: 2,122
southwest Mo.
wtd Offline OP
wtd  Offline OP

Joined: Jun 2002
Posts: 2,122
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
Re: P0430 code [Re: wtd] #4810119
07/10/18 11:27 AM
07/10/18 11:27 AM
Joined: Jun 2002
Posts: 2,122
southwest Mo.
wtd Offline OP
wtd  Offline OP

Joined: Jun 2002
Posts: 2,122
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
Re: P0430 code [Re: wtd] #4810189
07/10/18 12:11 PM
07/10/18 12:11 PM
Joined: Aug 2003
Posts: 13,432
NE,Ohio
Rand Offline
Rand  Offline

Joined: Aug 2003
Posts: 13,432
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.


2019 Jeep Cherokee Trailhawk 2.0T
Re: P0430 code [Re: wtd] #4810233
07/10/18 12:35 PM
07/10/18 12:35 PM
Joined: Dec 2006
Posts: 1,853
NY, NY
NYEngineer Offline
NYEngineer  Offline

Joined: Dec 2006
Posts: 1,853
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.

Re: P0430 code [Re: wtd] #4810236
07/10/18 12:36 PM
07/10/18 12:36 PM
Joined: Aug 2017
Posts: 798
MN
14Accent Online content
14Accent  Online Content

Joined: Aug 2017
Posts: 798
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.


2013 Chevrolet Volt - Saves enough in fuel to pay for itself!

2003 Cadillac Seville STS - The winter "beater", it uses the Volt's fuel
Re: P0430 code [Re: wtd] #4810242
07/10/18 12:40 PM
07/10/18 12:40 PM
Joined: Oct 2010
Posts: 1,625
stl
MarkM66 Offline
MarkM66  Offline

Joined: Oct 2010
Posts: 1,625
stl
Put an O2 spacer on it and forget it.

Re: P0430 code [Re: MarkM66] #4810317
07/10/18 01:49 PM
07/10/18 01:49 PM
Joined: Jan 2017
Posts: 2,546
VW Fanboy Island
maxdustington Offline
maxdustington  Offline

Joined: Jan 2017
Posts: 2,546
VW Fanboy Island
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.

Last edited by maxdustington; 07/10/18 01:50 PM.

03 Jetta AWP/09A 205k kms
Edge 0W40 + Mann 719/30
Re: P0430 code [Re: 14Accent] #4810838
07/10/18 11:12 PM
07/10/18 11:12 PM
Joined: Apr 2012
Posts: 6,306
MA
Wolf359 Online content
Wolf359  Online Content

Joined: Apr 2012
Posts: 6,306
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.

Re: P0430 code [Re: maxdustington] #4810847
07/10/18 11:22 PM
07/10/18 11:22 PM
Joined: Jun 2002
Posts: 2,122
southwest Mo.
wtd Offline OP
wtd  Offline OP

Joined: Jun 2002
Posts: 2,122
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
Re: P0430 code [Re: wtd] #4810850
07/10/18 11:25 PM
07/10/18 11:25 PM
Joined: Jun 2002
Posts: 2,122
southwest Mo.
wtd Offline OP
wtd  Offline OP

Joined: Jun 2002
Posts: 2,122
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
Re: P0430 code [Re: wtd] #4810865
07/11/18 12:14 AM
07/11/18 12:14 AM
Joined: Mar 2008
Posts: 7,910
USA
slacktide_bitog Offline
slacktide_bitog  Offline

Joined: Mar 2008
Posts: 7,910
USA
Aftermarket cats are not a problem as long as you're not burning oil smile

Re: P0430 code [Re: 14Accent] #4810969
07/11/18 07:17 AM
07/11/18 07:17 AM
Joined: Nov 2006
Posts: 21,258
MA, Mittelfranken.de
Trav Offline
Trav  Offline

Joined: Nov 2006
Posts: 21,258
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.


ASE L1, Master. Deutsch Meisterbrief.
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