Old tank of gas p0420,p0430
01-03-2015, 11:30 AM
#1
Old tank of gas p0420,p0430 Picked up a non running 2001 z28 for cheap, it had been sitting for a few months..
I ended up getting it started and the only 2 codes it has are p0420 & p0430 catalyst efficiency below threshold bank1/bank2
I highly doubt both cats went out at the same time and I'm hoping it's just the old gas in the tank
Car has 116k miles
Anyone else have similar problems with letting their car sit for too long?
I ended up getting it started and the only 2 codes it has are p0420 & p0430 catalyst efficiency below threshold bank1/bank2
I highly doubt both cats went out at the same time and I'm hoping it's just the old gas in the tank
Car has 116k miles
Anyone else have similar problems with letting their car sit for too long?
01-03-2015, 01:17 PM
#2
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Gas that's a few months old isn't great but isn't that bad either, if it was in truly bad shape then the engine wouldn't have run on it, or would run poorly. I always use Stabil for the garage queens because I know they'll be sitting for long periods, but there have been times where I've had various daily drivers sit for 1-3 months without prior knowledge and therefore no opportunity to treat them with Stabil - and the gas was still fine (and that's with local E10 fuel even).
Those codes don't come from aged or poor quality fuel. The PCM is comparing front O2 sensor readings to rear O2 sensor readings during a period of A/F adjustment, looking for comparative rear response time to determine if the cats have adequate oxygen storage capacity. If the rears respond to the A/F changes too quickly, then the cats have become a pass-thru without the ability to properly reduce emissions - thus you get a P0420/P0430. In some rare cases, people have found this code to be the product of a bad O2 sensor, but normally it's an issue with the cats. The cats on '00+ V8 F-bodies are known to fail in this way; coatings wear off the substrate causing the increase in tail pipe emissions that trigger this code (my '02 did this as well, right around 100k). GM issued a warranty extension for this reason, but that expired after the cars were 10 years old. So yes, it's entirely possible that the cats are both below threshold and will need to be replaced if you have a sniffer test to pass (I assume so, being in CA). I was able to ignore mine since we don't have a sniffer here.
Those codes don't come from aged or poor quality fuel. The PCM is comparing front O2 sensor readings to rear O2 sensor readings during a period of A/F adjustment, looking for comparative rear response time to determine if the cats have adequate oxygen storage capacity. If the rears respond to the A/F changes too quickly, then the cats have become a pass-thru without the ability to properly reduce emissions - thus you get a P0420/P0430. In some rare cases, people have found this code to be the product of a bad O2 sensor, but normally it's an issue with the cats. The cats on '00+ V8 F-bodies are known to fail in this way; coatings wear off the substrate causing the increase in tail pipe emissions that trigger this code (my '02 did this as well, right around 100k). GM issued a warranty extension for this reason, but that expired after the cars were 10 years old. So yes, it's entirely possible that the cats are both below threshold and will need to be replaced if you have a sniffer test to pass (I assume so, being in CA). I was able to ignore mine since we don't have a sniffer here.
01-03-2015, 01:22 PM
#3
Gas that's a few months old isn't great but isn't that bad either, if it was in truly bad shape then the engine wouldn't have run on it, or would run poorly. I always use Stabil for the garage queens because I know they'll be sitting for long periods, but there have been times where I've had various daily drivers sit for 1-3 months without prior knowledge and therefore no opportunity to treat them with Stabil - and the gas was still fine (and that's with local E10 fuel even). Those codes don't come from aged or poor quality fuel. The PCM is comparing front O2 sensor readings to rear O2 sensor readings during a period of A/F adjustment, looking for comparative rear response time to determine if the cats have adequate oxygen storage capacity. If the rears respond to the A/F changes too quickly, then the cats have become a pass-thru without the ability to properly reduce emissions - thus you get a P0420/P0430. In some rare cases, people have found this code to be the product of a bad O2 sensor, but normally it's an issue with the cats. The cats on '00+ V8 F-bodies are known to fail in this way; coatings wear off the substrate causing the increase in tail pipe emissions that trigger this code (my '02 did this as well, right around 100k). GM issued a warranty extension for this reason, but that expired after the cars were 10 years old. So yes, it's entirely possible that the cats are both below threshold and will need to be replaced if you have a sniffer test to pass (I assume so, being in CA). I was able to ignore mine since we don't have a sniffer here.
01-03-2015, 02:08 PM
#4
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Originally Posted by Burken01
Quick question, I found some cats locally 2000 ss..
If I swap them onto my 01 z28 will it pass smog if he looks at the serial #
Do you know if they are direct interchangeable?
If I swap them onto my 01 z28 will it pass smog if he looks at the serial #
Do you know if they are direct interchangeable?
I don't see how a smog tech would be able to tell the difference between model year 2000 cats and model year 2001, as they are externally identical and use the same GM part number. But I have never lived in CA, nor do I have any personal experience with CA state inspections.
01-03-2015, 03:48 PM
#5
The entire exhaust system is interchangeable from 2000-2002, with the exception of the passenger side exhaust manifold (same exact design, except that the '00 version has the provision drilled out for the EGR tube, and this provision is not drilled for '01/'02 as there is no EGR). I don't see how a smog tech would be able to tell the difference between model year 2000 cats and model year 2001, as they are externally identical and use the same GM part number. But I have never lived in CA, nor do I have any personal experience with CA state inspections.
01-03-2015, 05:31 PM
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If they are used, then there is a risk that they are no better than the ones you are removing, as all '00-'02 cats are subject to the issue. Hopefully they are from a lower mileage car. You wouldn't be able to tell the condition of the substrate coatings by looking at them, so it's going to be hit or miss if they aren't brand new (unless you're first able to check for these same codes on the car they are being removed from).
01-03-2015, 05:34 PM
#7
If they are used, then there is a risk that they are no better than the ones you are removing, as all '00-'02 cats are subject to the issue. Hopefully they are from a lower mileage car. You wouldn't be able to tell the condition of the substrate coatings by looking at them, so it's going to be hit or miss if they aren't brand new (unless you're first able to check for these same codes on the car they are being removed from).
If they don't work, I know where I can recycle them to make back my money
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01-07-2015, 09:54 AM
#8
If they are used, then there is a risk that they are no better than the ones you are removing, as all '00-'02 cats are subject to the issue. Hopefully they are from a lower mileage car. You wouldn't be able to tell the condition of the substrate coatings by looking at them, so it's going to be hit or miss if they aren't brand new (unless you're first able to check for these same codes on the car they are being removed from).
Got the new cats 75k miles
They look like they've been sitting for awhile and when I tipped the passenger side cat it had a little moisture in it dripping out. If I had to guess it was a couple cap fulls.
Maybe the dew? I'm letting it drain today upside down..
What are your thoughts? Oh and it was just the passenger side cat
01-07-2015, 01:49 PM
#9
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Short of any obvious physical damage/melting/cracking/massive gunk build-up, there really isn't any visual way to test a cat for proper operation.
01-08-2015, 01:21 AM
#11
Installed the new/used cats, same codes popped up 2 miles down the road..
It can't be the 02's since they have to be working to even perform the cat test..
I have one more pair of used cats to try, the cleanest set of the bunch lol
Sheesh I just want to pass smog for 1 day and then I'm ripping all this crap out for some LT's
Help me car gods
It can't be the 02's since they have to be working to even perform the cat test..
I have one more pair of used cats to try, the cleanest set of the bunch lol
Sheesh I just want to pass smog for 1 day and then I'm ripping all this crap out for some LT's
Help me car gods