The Official Blown Catalytic Converter Thread

[<3S4PLAY]

Well it seems as if this is becoming a more common problem, as there are few threads that have popped up recently with member's reporting failed/blown catalytic converters on their cars. I am sure like the rest of you, I thought that it would never happen to my S4, especially with the amount of miles i'm currently at(63k miles). I would really like to start this thread to see if we can collect more data on failures and try to come to a better conclusion as to why the cat's on our vehicle are failing prematurely.

Over the weekend during a grocery store run, I had noticed that the tone of my Corsa exhaust sounded a bit different. It was much deeper than normal. At first I chalked it up to maybe a loose exhaust clamp and that i would tighten it up later on when I got home, but when I stepped out my vehicle I noticed a very strong smell of gas very similar to my STI with a catless exhaust. At this point I still chalked it up to a possible exhaust leak and thought nothing more of it.

But on my way home, the CEL pops on in my dash. I pull in to my garage and immediately pull the code via VCDS and im getting a P0420 Catalyst System Efficiency Below Threshold (Bank 1) error. I also notice that the rear of the vehicle and exhaust is covered in a layer of white/grey metallic dust.

The car was washed and clean prior to going to the grocery store. Here is what it looked like after a 20 mile round trip:



I did a quick search and all of my symptoms point to a failed/blown cat. I understand that the catalytic converters on our vehicles are covered for 8 years/80k miles. Problem is, my car is fairly modified, as I am currently running a stg 2 tune. If Audi is willing to replace the cat's under warranty that would be awesome, but I fully understand that you have to pay to play, and I am more than willing to pay up to get new cats installed at the dealership or at my local tuner shop. What I want to get down to is why this is happening, and what we can do to prevent it from happening to others.

If you have had your cat's fail please post in this thread so that we can collect a bit more info on this issue.

[Rodizzle]

Driver side cat failed on me @45k , prior to that I would get the EPC light/limp mood . Work was done under warranty . Now I'm afraid the left cat might fail anytime . I'm currently at 52k .

2014 DSG.


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[<3S4PLAY]

Rodizzle did you have any mods done when the first cat failed?

Did the car have any symptoms prior to the first cat failing?

Just curious which Bay Area dealership did the warranty replacement on your car?

[MikeIC23]

The passenger cat is blown on my 2010, 61K miles and has been rattling for the last 10K. Still deciding what I want to do, replace with stock unit that will likely blow out again or go high flow and risk having an exhaust smell/CEL/trouble passing emissions on my daily driver.

Interestingly, no check engine light is being displayed on my car. APR Stage 2 (supercharger pulley) since 32K miles.



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[Rodizzle]

My transmission had failed at 45k , when picked it up from Audi of Oakland and heading back home . I kept hear a noice like a lose exhaust gasket . Keep I'm mind before the new noise and new transmission I was getting the epc light , I just thought it was bad gas or the chipwerk pro ( only mod ) . Long story short , took it back to Oakland where the kept the car for a week trying to see where this noise was coming from because the vehicle wouldn't throw a code . So not until they insert a camera through the oxygen sensor they found out that my cat was shot.



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[B18b1ex]

My Passenger one went at around 65K, i argued and fought for both to be changed. I would bet the occasional EPC light but no DTC so they would not change them, until after the car belched out a huge amount of white dust twice in on night and i had it on camera. I think the video helped get both changed at the same time. CPO warranty.

[bokiboki]

I think I asked this question in another thread but never got the answer - are these Magnaflow cats direct replacement or high flow ones? https://www.ecstuning.com/b-magnaflo...eft/49135~mag/

And did anybody that installed them pass the emission tests in NY State, no oxygen spacers needed? Thanks.

[jl87]

Good question, if you check out the description on ECS it says California compliant, but then when you check on MF's website it just says Fed, so I'd assume you'd have no issues in NY. I'd also venture a guess they're an OE replacement.

[<3S4PLAY]

The magnaflow cats is an aftermarket direct replacement part and you should have no problems with it passing an emissions test in NY.

On the other hand, it doesn't appear to be a viable option for those who live in California

[DUMPMOUT]

Anyone have blown cats they are trying to get rid of? Looking to gut

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[Kustomimports]

Put test pipes on. And purchase a good aftermarket cat, if you want. Open it up for better flow... the tiny 1.34 piping is tiny and restrictive

[onlyaudis]

Well it seems as if this is becoming a more common problem, as there are few threads that have popped up recently with member's reporting failed/blown catalytic converters on their cars. I am sure like the rest of you, I thought that it would never happen to my S4, especially with the amount of miles i'm currently at(63k miles). I would really like to start this thread to see if we can collect more data on failures and try to come to a better conclusion as to why the cat's on our vehicle are failing prematurely.

Over the weekend during a grocery store run, I had noticed that the tone of my Corsa exhaust sounded a bit different. It was much deeper than normal. At first I chalked it up to maybe a loose exhaust clamp and that i would tighten it up later on when I got home, but when I stepped out my vehicle I noticed a very strong smell of gas very similar to my STI with a catless exhaust. At this point I still chalked it up to a possible exhaust leak and thought nothing more of it.

But on my way home, the CEL pops on in my dash. I pull in to my garage and immediately pull the code via VCDS and im getting a P0420 Catalyst System Efficiency Below Threshold (Bank 1) error. I also notice that the rear of the vehicle and exhaust is covered in a layer of white/grey metallic dust.

The car was washed and clean prior to going to the grocery store. Here is what it looked like after a 20 mile round trip:



I did a quick search and all of my symptoms point to a failed/blown cat. I understand that the catalytic converters on our vehicles are covered for 8 years/80k miles. Problem is, my car is fairly modified, as I am currently running a stg 2 tune. If Audi is willing to replace the cat's under warranty that would be awesome, but I fully understand that you have to pay to play, and I am more than willing to pay up to get new cats installed at the dealership or at my local tuner shop. What I want to get down to is why this is happening, and what we can do to prevent it from happening to others.

If you have had your cat's fail please post in this thread so that we can collect a bit more info on this issue.

I noticed APR does not recommend running stock cats with stage 2 tunes.

[fitzydude]

Does anyone have advice on how to make the cats fail in such a way that the catalyst melts or dislodges leaving leaving a high flowing gutted cat housing

[B18b1ex]

Does anyone have advice on how to make the cats fail in such a way that the catalyst melts or dislodges leaving leaving a high flowing gutted cat housing

When mine failed it was completely empty, no sign of material left behind.

[cspcrx]

^ free performance upgrade!

[B18b1ex]

^ free performance upgrade!

If I were tuned with a program that kills the DTC light maybe but that thing is annoying. :) So had both replaced.

[miztahsparklez]

I went through many..... Replacing with OEM will just happen again.


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[cjw]

Amy trends on the tune?

What are the best aftermarket options that are durable?

[<3S4PLAY]

I went through many..... Replacing with OEM will just happen again.


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How many miles we're your replacement cat's lasting you? What tune were you running?

[cspcrx]

If I were tuned with a program that kills the DTC light maybe but that thing is annoying. :) So had both replaced.

I believe others have just added spaces on the O2 sensor and it eliminates the code.

[DBL R]

Does anyone have advice on how to make the cats fail in such a way that the catalyst melts or dislodges leaving leaving a high flowing gutted cat housing

That would be nice

[protogeoff]

I believe others have just added spaces on the O2 sensor and it eliminates the code.

I'm curious what spacer is working. It seems like a bit of a black art getting the correct pullback for the sensor.

V1Rotate

[4Rings3Liters]

I too am curious on a way of running catless with no codes?

[miztahsparklez]

I was running APR stage 2, then 034.

My first one went out around 35-40k, then it was like 45-50, and another 10k after that. Lol.

Finally, I just relocated to the bottom of the car so I can replace much easier.


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[Loe]

you can either run a very small spacer or simply purchase Area74 O2 simulators.

[CELison]

Both mine failed before 75k

[4Rings3Liters]

you can either run a very small spacer or simply purchase Area74 O2 simulators.

Will the car still be able to pass a state inspection?

[miztahsparklez]

Will the car still be able to pass a state inspection?

Not if they check visual....


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[cchoi83]

I was running APR stage 2, then 034.

My first one went out around 35-40k, then it was like 45-50, and another 10k after that. Lol.

Finally, I just relocated to the bottom of the car so I can replace much easier.


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Were any of these replaced under factory warranty?

[miztahsparklez]

Were any of these replaced under factory warranty?

The first 3 sets, but if you had a tune on the car, they may not warranty it.


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[cchoi83]

The first 3 sets, but if you had a tune on the car, they may not warranty it.


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I'm aware but I was just curious because of the relatively short mileage intervals you had.

[miztahsparklez]

I'm aware but I was just curious because of the relatively short mileage intervals you had.

The last time I had the dealer change it they said AOA was going to have to check out the car before they warranty the cats again.


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[cchoi83]

The last time I had the dealer change it they said AOA was going to have to check out the car before they warranty the cats again.


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That's good to know. Thanks.

[Loe]

Will the car still be able to pass a state inspection?

visual no (unless you gut your current cats to maintain OEM look), sniffer no. But from a scanning perspective, a small spacer should set readiness. If not, then the more expensive Area74 active sims should help (but I do find them finicky at times).

[Mat@1975]

Hello !

My actuel Question is : What is the way to blow both Cats at the same time ! ;) (when i mean blow, it's blow and then be empty like it often happens)

Another question is : can we drive with only 1 cat gutted and the other OK, waiting for this second also to fail ?

BR

Mat

[whiped]

I have the same questions as Mat.

I've thought about pulling the Cats off and gutting them myself but it seems like a chore.

You could probably remove the 02 sensors on the top of the cats and shove something in there to mess up the integrity of the honeycomb to help blow it out.

[Loe]

ceramic cats hate water...fwiw

[fitzydude]

ceramic cats hate water...fwiw

So you're saying pull the spark plugs, hook up a garden hose to the intake, and crank it over?

PS: My cat at home hates water too, but he's a little asshole.

[db12]

So if your cats blow does it actually improve performance due to increased airflow or can they actually "clog"?

[whiped]

So you're saying pull the spark plugs, hook up a garden hose to the intake, and crank it over?

PS: My cat at home hates water too, but he's a little asshole.

I wouldn't do that. I'd remove the 02 sensors and spray some water that way.

I'm in for results Alex.