Catalytic Converter Cleaner?
04-20-2015, 09:17 AM
#1
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Troubleshooting Fault Codes P0421 & P0431
Inspection is due this coming weekend. My catalytic converter is giving the Efficiency Below Threshold Fault Code, but I strongly believe the Catalytic Converter Fault Code is a False Positive. 
I'm noticing that the engine fault codes P0421 & P0431 appear before the Misfires are detected by the ECU.
Please let me know which further information should be posted here for further analysis and discussion. Thank you.
I'm noticing that the engine fault codes P0421 & P0431 appear before the Misfires are detected by the ECU.
Please let me know which further information should be posted here for further analysis and discussion. Thank you.
Last edited by arjun90; 04-21-2015 at 06:03 AM. Reason: Title Change
04-20-2015, 11:51 AM
#2
Too late. You will be hard pressed to get your readiness codes set after a reset.
Forget the cleaner, you need to make sure your plugs and air filter are good (minimize misfires and lean out the mixture (within reason), then reset the code and take a few long high-speed drives to get the cats as hot as possible.
See when the code comes back, the reset and drive it like that again, about 1/2 as long and get yourself smogged before the code shows up.
Forget the cleaner, you need to make sure your plugs and air filter are good (minimize misfires and lean out the mixture (within reason), then reset the code and take a few long high-speed drives to get the cats as hot as possible.
See when the code comes back, the reset and drive it like that again, about 1/2 as long and get yourself smogged before the code shows up.
04-20-2015, 12:14 PM
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Thank you for the practical advise, 
Too late. You will be hard pressed to get your readiness codes set after a reset.
Forget the cleaner, you need to make sure your plugs and air filter are good (minimize misfires and lean out the mixture (within reason), then reset the code and take a few long high-speed drives to get the cats as hot as possible.
See when the code comes back, the reset and drive it like that again, about 1/2 as long and get yourself smogged before the code shows up.
Forget the cleaner, you need to make sure your plugs and air filter are good (minimize misfires and lean out the mixture (within reason), then reset the code and take a few long high-speed drives to get the cats as hot as possible.
See when the code comes back, the reset and drive it like that again, about 1/2 as long and get yourself smogged before the code shows up.
04-20-2015, 01:46 PM
#4
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some people have had good results with post cat 02 spacer.
Inspection is due this coming weekend. My catalytic converter is giving the Efficiency Below Threshold Fault Code, and wanted to know which catalytic converter cleaner would be appropriate. I know adding additives to our Audi's is never a good thing, but I feel this is necessary for the time being since time is short right now and I strongly believe the Catalytic Converter Fault Code is a False Positive.
STFQ regarding this fix.
04-20-2015, 02:21 PM
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I've had some moderate success earlier with filling the tank half full then giving it a bottle of condensation remover additive (water buster etc, not sure what they call it where you are). If there's an actual issue, it is extremely unlikely to fix anything (unless water slight condensation in tank is the actual issue) - but it often masks the issue temporary to get it passed the issue. You'll also want to give it a good drive, let it taste WOT and some revs. Afterwards, check plugs and replace if they're not looking too good.
If you have VCDS/Vag-com, might want to check long term/short term fuel trim, see if its compensating for something. Get a cigar, plug the intake at the airbox connection, pull one of the vacuum hoses and blow smoke in there (whatever pressure your lungs can generate won't hurt the seals). Plug hose end with tongue/finger and check for smoke leaks (=vacuum leak). Fix any of said vacuum leaks.
"End user remedies" for cleaning cats, is AFAIK, a myth. Anything abbrasive enough to clean up carbon deposits in there, is more than likely to also strip away the various unobtanium coatings that make the whole thing work.
If you have VCDS/Vag-com, might want to check long term/short term fuel trim, see if its compensating for something. Get a cigar, plug the intake at the airbox connection, pull one of the vacuum hoses and blow smoke in there (whatever pressure your lungs can generate won't hurt the seals). Plug hose end with tongue/finger and check for smoke leaks (=vacuum leak). Fix any of said vacuum leaks.
"End user remedies" for cleaning cats, is AFAIK, a myth. Anything abbrasive enough to clean up carbon deposits in there, is more than likely to also strip away the various unobtanium coatings that make the whole thing work.
04-20-2015, 04:12 PM
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I'm convinced that these so called additives may be just an added hassle. How does this differ from Seaform. Can't you add Seaform straight to the gas tank to alleviate some part of the emissions system? I'll be receiving the genuine Audi Additive later this week to add to the gas tank after replacing the spark plugs.
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04-20-2015, 04:29 PM
#8
I don't know what Seafoam is made of.
Most fuel system cleaning additives are petroleum based solvents. They dissolve deposits and (mostly) burn in the cylinders, but what does not burn increases the hydrocarbon load the cat has to deal with.
Dry-Gas, and other fuel system water displacers are mostly alcohol, they will dissolve any moisture and as long as the water load is not too high will burin off very efficient.
Basic chemistry, like what you (were supposed to have) learned in high school.
Most fuel system cleaning additives are petroleum based solvents. They dissolve deposits and (mostly) burn in the cylinders, but what does not burn increases the hydrocarbon load the cat has to deal with.
Dry-Gas, and other fuel system water displacers are mostly alcohol, they will dissolve any moisture and as long as the water load is not too high will burin off very efficient.
Basic chemistry, like what you (were supposed to have) learned in high school.
04-20-2015, 05:29 PM
#9
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arjun90 what are the post O2 values on the diagnostic tool you are using?
My point is that the pre O2 values compared to the post values will tell you if your cats are going south and should not be the same or even close indicating that the cats are not removing hydrocarbons at the accepted level standard, SloopJohnB mentioned spacers that can correct the post O2 sampling within the 5% margin that is probably flagging the efficiency code (I believe it's 5%), the other issues could be the sensors going bad also.
Look I'm not trying to be a ***** but you are FLOGGING this forum with many inundations of problems and WE are trying to help you but you are ALL OVER THE BOARD with the replies leading into even non-relevant questions and comments outside of the thread subject, try to systematically follow the advice and systematically answer so WE can guide you towards a logical remedy that works.
Forget the cat cleaning additives! It's noting but SNAKE OIL and a waste of $$
My point is that the pre O2 values compared to the post values will tell you if your cats are going south and should not be the same or even close indicating that the cats are not removing hydrocarbons at the accepted level standard, SloopJohnB mentioned spacers that can correct the post O2 sampling within the 5% margin that is probably flagging the efficiency code (I believe it's 5%), the other issues could be the sensors going bad also.
Look I'm not trying to be a ***** but you are FLOGGING this forum with many inundations of problems and WE are trying to help you but you are ALL OVER THE BOARD with the replies leading into even non-relevant questions and comments outside of the thread subject, try to systematically follow the advice and systematically answer so WE can guide you towards a logical remedy that works.
Forget the cat cleaning additives! It's noting but SNAKE OIL and a waste of $$
04-21-2015, 03:20 AM
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Thank you jcman,
I have the XTool VAG401; As per Ross-Tech Data Blocks 30-49 contains all the oxygen sensor (lambda values) and catalytic converter information. Please let me know which information is required for further analysis and discussion on this thread.
Data Block 100 indicates the O2 Sensor as passed (0) as per the 8-bit readiness. (1) would indicate a fault.
Please let me know if I should create a new thread, or if I should change the title on this one.
I have the XTool VAG401; As per Ross-Tech Data Blocks 30-49 contains all the oxygen sensor (lambda values) and catalytic converter information. Please let me know which information is required for further analysis and discussion on this thread.
Data Block 100 indicates the O2 Sensor as passed (0) as per the 8-bit readiness. (1) would indicate a fault.
Please let me know if I should create a new thread, or if I should change the title on this one.
arjun90 what are the post O2 values on the diagnostic tool you are using?
My point is that the pre O2 values compared to the post values will tell you if your cats are going south and should not be the same or even close indicating that the cats are not removing hydrocarbons at the accepted level standard, SloopJohnB mentioned spacers that can correct the post O2 sampling within the 5% margin that is probably flagging the efficiency code (I believe it's 5%), the other issues could be the sensors going bad also.
Look I'm not trying to be a ***** but you are FLOGGING this forum with many inundations of problems and WE are trying to help you but you are ALL OVER THE BOARD with the replies leading into even non-relevant questions and comments outside of the thread subject, try to systematically follow the advice and systematically answer so WE can guide you towards a logical remedy that works.
Forget the cat cleaning additives! It's noting but SNAKE OIL and a waste of $$
My point is that the pre O2 values compared to the post values will tell you if your cats are going south and should not be the same or even close indicating that the cats are not removing hydrocarbons at the accepted level standard, SloopJohnB mentioned spacers that can correct the post O2 sampling within the 5% margin that is probably flagging the efficiency code (I believe it's 5%), the other issues could be the sensors going bad also.
Look I'm not trying to be a ***** but you are FLOGGING this forum with many inundations of problems and WE are trying to help you but you are ALL OVER THE BOARD with the replies leading into even non-relevant questions and comments outside of the thread subject, try to systematically follow the advice and systematically answer so WE can guide you towards a logical remedy that works.
Forget the cat cleaning additives! It's noting but SNAKE OIL and a waste of $$
Last edited by arjun90; 04-21-2015 at 05:54 AM.