In regard to 0:56 I know exactly why Audi choose to place the converters where they are. Basic engineering says the faster a catalytic converter can heat up the more quickly the car will produce clean air out of the tailpipe. The goal is to get the vehicle into closed loop operating as quickly as possible for emissions reasons as well as for wear reasons because when the car runs in open loop you are wasting fuel and diluting engine oil. Faster warm up times are one of the many factors that contribute to the fact we can now get away with changing our oil at 10k + intervals. Also, a hot converter will clean itself better which is probably why these engines can eat 1qt of oil every 600 miles and still not set off a catalyst efficiency codes which has always shocked me since oil does contaminate converters (it says so on your oil filler cap). Oil consumption is probably a huge part of the failure of the original part.

Where’s a cat thief when u need em

Knowledge of how to maintain these cars is key and I feel like you’re gonna save so many cars with this series Cam

please never delete these videos!! this knowledge is priceless. Thank you for sharing

My B6 VR6 Passat had a similar exhaust system but with 4 cats. Thankfully they lasted well over 300k till the trans started slipping. Thanks for your vids, I really enjoy your C7 content.

As a new owner to an A6 exactly like yours, these videos are super helpful. Thank you so much! Definitely subscribing

Such an underrated channel! Appreciate the videos!

Great write up on it! I had worked at an Audi dealer for several years up until 2021. While I had replaced several sets of cats for catalytic inefficiency faults and cracked flange welds, I had never seen them be the cause of any drivability concerns. After 2021, I had went to an Indy euro shop where I still currently work. It wasn’t until I started actually modifying em where I’ve seen em start to have issues. So far, I’ve only seen 3.0 cats be the cause of an engine failure, which was on an APR stage 3 build. For what it’s worth, I live in one of the hottest and humid climates in the states. In my opinion and experience with these, if it’s modded, ditch em. If not, don’t sweat it! 😁😁

Dude, this has been happening to my car for years!!! Finally, someone who knows what the problem is!!! Thank you!!!!!!!!! It's a 2012 :)

Another great video, very informative! Question - How's about a recommendation or video on what you recommend should be the first upgrades or maintenance items on the C7. Surely you have a list of things needing to be addressed right off the bat. Cheers to more great content!

This is very true. I had melted pistons all in bank 2 of the engine #6 piston was the worst. My catalytic converter was clogged and it caused my combustion chamber to reach really high temperatures. I did not experience any misfires or rattles until after the damage was done. My data log showed that my cars was running perfectly fine during racing. I learned the hard way

2012 A7, OEM Cats, 155k miles, stage 2 DP since 110k. Fearing the day this happens!

Great advise, actually one I’ve thought of often and was more on the side of gutting the cats on my stick system. Good thing is that my car sits at home in the days and I drive a work van, so it’s out sporadically on weekends more than anything else, ( only mods are APR 1 & K&N)

Great video! I've heard some people say if you go stage 1 you don't need to do anything to your catalytic converters and like what you're saying if you just boot it a lot (send it) you're at risk. I bought my S4 because of how much fun it is to send it so I'm always booting it. I appreciate you explaining everything in great detail. I am not in an area where I need to pass emissions, but I don't want my exhaust to be louder either. But higher on my list is cost I don't want to spend good money on something that'll fail again down the road. Sounds like I'm going gutted cats, the wife is going to love it haha.

Does driving with a Check Engine Light from having test pipes hurt anything? Perhaps messing with Air/Fuel mixture? Which would you recommend as far as safety? Not trying to switch tuners right now, and my tuner does not have a test pipe file. Bonus question: the SAI system. If I have test pipes, are the SAI ports less likely to clog? And if they do, would it even matter in my case?

Hello, very helpful video, i wish i knew this things before. I have A6 C7 with 2.8FSI engine(very similiar to 3.0TFSI but without superchager). Last week when I accelerated uphill, catalyst literally disconect from exhaust manifold. We had to put whole engine from car because there was no place to repair it on car. When we looked on catalyst, it was disconnected from pipe. There wasnt any welds! We had to weld it and other side too for sure. I dont understand why Audi didnt weld it. Decat does not come to mind because of emmision tests every 2 years in our state. I am glad we could repair it and i am glad also that cats were okay because 1cat costs around 2400€. Total price was 1300€ for the repair (because of engine pulling out) but it is still better than buy new ones.

This is a great video. Unfortunately, I watched it too late and fell victim to this resulting in catastrophic failure and a blown engine. I bought a 2012 A6 3.0T and went APR Stage 2 with tune and dual pulleys. It was great fun for a few years until it started running rough with misfires. My Indy shop also must not have seen your video and kept replacing coils etc. Then came cylinder 6 catastrophic failure due to exhaust manifold bits going into cylinder I'm guessing. Went the route of putting in a used engine and I pretty much baby the car at this point. Need to show my mechanic this video and address the cat issue before the same thing happens all over again. Thank you for your insight and great video!

Very good information on Cat's. My question is, when you start upgrading power with tuning and pulley's is it a good practice to gut cat's or upgrade exhaust system first? Also, is there a diy way to check condition of Cat's? 2012 A6 prestige sports 3.0t 80k

Thanks for this video. Although I'm looking at a B8.5 it was very helpful regarding the motor.

I've had my S4 for almost 3 years now (2014) and was told by my shop when I bought it that the slight rattle I was hearing on startup was some of the honeycomb that had broken off of my passenger side cat and was rattling inside. So far it seems to be fine, and I haven't thrown any codes as a result, but it has always bothered me and been in the back of my mind that it could give out. I am running an APR stage 1 tune, and have been considering going single or dual pulley, but I would probably also need to do something about the cats at that time as well. What I had been considering were the Magnaflow high-flow cats, but I was viewing that as a 'permanent' solution and wasn't aware that those would inevitably fail as well. I guess I need to look into the local laws about emissions standards and if I can get away with test pipes... thanks for this useful info!

Very informative video! My car has a vibration at idle but gone with I get to speed.. another thing I wanted to note is that when I start to slown down and at around 2-1200rmps it get worse could it be the cats being clogged ? Thanks and keep up the good worrk!

I unfortunately had the same problem, which converter do you recommend can you give a link. thanks in advance

Hi Sir very informative video... Tell me someting.. I have a 2011 A6 2.0tfsi... Should i gut out my cat before it clogs? Or do I have to tune the ECU inorder to do so? Also would the car have any performance problems by gutting out the cat converter...?

93,400 miles stock 2014 Audi Q5 3.0t mostly highway mile, any of this apply to my vehicle? Preventative service beyond manufacture recommendation? If I go stage 1 does it change maintenance and repairs? Thank you!

great info. thinking about moding my A7 and hadn't thought about the cat. great heads up. thank you so much for the vid.

My A7 3.0T has gutted cats but since here in EU it doesnt pass the emissions the last owner had to put universal cats on it(a little bit further away from the engine). It has "custom" exhaust also with deleted o2 sensors(also deleted in the map so no check engine light). The thing is I changed the universal cats(they were like the cheapest ones) with euro5 universal cats but I've been told that those wont last very long either. What would the best plan be, should I get some more expensive sport cats there? What would be the best choice out there that is not very expensive and is available in EU also.

I have a 2017 Sq5 with 80k dual pulley, just got check engine code -0430, and white smoke from exhaust. Now I have CAP test pipes coming in Friday, going to be attempting to tackle the job. The rasp I'm worried about but I don't really have a choice, currently running stock downpipes and awe catback touring. Good luck with your current engine build!

Hey, love your videos! You have a great channel! Question, I have a 2012 Q7 with the 3.0t and I’d like to stage one jackal tune it and maybe stage two down the road…on the q7 as well do you recommend gutted cats? And do you have any heat exchanger recommendations for the q7?

Incredible video. I was able to get in on the test pipe GB thanks. Im in NY and plan on getting generic cats and install them on my non-reson downpipes to hopefully pass NY OBD emissions and kill the rasp. Hopefully with test pipes and generic cats along with the MF x-pipe and resonator I can accomplish both my goals.

Great video. I’m from the UK and drive a 2011 S5 3.0tfsi. Are there any manufacturers/brands you recommend for test pipes and for the high flow cats to deal with the noise? My understanding is the engine is very raspy if you just fit test pipes on there own. Any help would be massively appreciated as one of my cats is failing. Thanks

My B8.5 SQ5 is still on stock cats after 100k miles on Stage 2+ tune. I hope they don't fail on me any time soon cause I'd hate to go through the trouble on getting them replaced! I remember when I went to Stage 2+ a lot of people told me to remove the cats since I lived in a high heat climate but I've had no issue with them so far. Thanks for the tip on the aftermarket test pipes with cats! If mine end up failing I'd probably just replace them with OEM ones.

awesome info. Having issues though… had a bad coolant leak that did hydrolock. So new pcv thermostat water pump valve cover gasket intake manifold gasket… Major cleaning and oil flushes. Vehicle runs fine but now i have misfire on 3 and 6. you have two videos that are taking me to different ways. is it the super harder intercooler leak? or is it the clogged cats? I did have cat codes during all this rehab. I really am at a loss at what to do. it’s a 2014 a7 with 91k bought at auction this way. any advice would help! thanks in advance

I have 2011 S5 and had this issue. Passengers side cat was busted.. Audi charged me +4000€ to replace a new one.. only the cat cost over 2000€. Not a cheap car to repair. I hope that drivers side cat won't fail on me soon too :D Thanks for great video! I hope I watched this earlier.

Great video! Got some misfire on cylinder 1 and 3 couple days ago. Already scheduled a service for carbon cleaning and new fuel injectors but still worrying about cats. Do you have any suggestion for getting a high flow cat? What brand would you recommend or what product? Thank you so much!

Good Evening, I have a 2017 a7 c7.5 competition stage 2 ( intake, x-pipes ) . So I may get the same issues one day ? I’m planning to get AWE touring Edition exhaust with resonated downpipes. Thank you !

Just hit 67k miles on my stock s5. In California so emissions are a pain, if I don’t plan on going w/ performance mods and don’t abuse it could I see the cats lasting a while longer? great video as always 👍🏼

Great video! Very well explained

Commenting on adding a downstream CAT, wouldn't you just get a CEL from the O2 sensor or if you add it downstream you would also need to add the spacers?

I have a ‘16 C7.5 with around 65k miles. Totally stock, driven hard on occasion for short periods of time, but pretty casual most of the time. Haven’t noticed any oil consumption issues or misfires. Should I be concerned about this yet?

Excellent video and info as usual Cam! Question, do additives like Cataclean every quarter help at all?

Great video, I'm glad i found your channel! I just upgraded from my 2009 a4 to a 2014 a6 3.0T, i love it and I'm trying to take care of it for as long as possible but I'm still learning a lot about the car. At 9:08 you mention the 3 ways you can mitigate the failure of the catalytic converter. My question is, which of the 3 ways is the best and also which is the most cost effective to have done at a local shop? Do you also know the average price I would spend on each? I also looked into the test pipes on can auto and it says that they increase performance but earlier in this video you mentioned that increased performance can quickly wear on the catalytic converters, does that apply with this as well? Thanks in advance, love your videos!

Sucks to be in cali like me. Soo many unnecessary restrictions

Thank you I been dreaming of having a 3.0 tfsi engine

How did you manage to deal with the O2 sensors after gutting the cats? Is it possible to tweak the ECU, so that it acts as if everything is fine without popping any CELs?

Mine did the same thing you were saying about a month ago changed the plugs and coils and it has been fine but now after hearing it makes sense. I only had a misfire in cylinder 1 and 3. However I’m in the military and idk where I could get stationed so I’m scared of failing emissions tests. What would you recommend?

So, I bought a '13 S4 a few months ago, had no issues during the summer, but as soon as it got cold I had a PCV warning about insufficient airflow, solved that by relocating the hose coming from it up by the passenger side quarter panel. and removing that cover over the intake for increased airflow. Since then, no PCV warnings, but I replaced the water pump and had a transmission service done, and now, whenever it's foggy out, or raining, I get a transmission error code/warning that says not to use reverse, and then the TPMS light comes on for a second and then they both go away, but TPMS will keep popping up every other minute until I turn off and restart the car.... please help

Excellent information! Thank you.

Hey I need some help! I’ve been saving up for a s4 3.0t for a while now and not one time have I thought about searching up for the common problems until now. I live in California so tampering with the catalytic converter is already a problem so what would you suggest for me to do that could prevent them from failing and that would still allow me to pass emissions over here? Thank you if you can help out!

I have a slight rattle at certain RPMs and wonder if it might be leaking some exhaust gases pre/post converter. No codes, misfires etc. Does this seem accurate? Great content as always!!!

i did say this before on one of your videos (i live up north too ND, and we get a lot of salt calcium chloride on the road in the winter) there is an easy way to take them out: take your firewall off (takes about 1 hour if you unplug the engine wire harness from the fuse/relay box) that compartmentalizes your engine bay from the washer fluid and brake fluid reservoir and you have so much space to take them out , you won't believe. i took my cats out 3 times out that way and it took me 2.5h to take both of them off( granted i was lucky and i didn't strip the 3 copper nuts at the top) last time i took them off i upgraded to the cenex exhaust that you had in one of your videos

So does this also happen to 23 Q7 models with the 3.0 engine?

Luckily I don't have emissions to worry about and I did would you did on one of my vehicles cut the cats out gutted them and had them welded back in and everything was great. I'm thinking like you said that's the way to go besides removing some resonators and changing the factory mufflers but I don't really want a ton of drone in the car so any input is greatly appreciated

The test pipe route tends to make the car sound raspier and less refined. Yet I can't find any high flow catalytic converters for this platform. Do you know if there are any cats to replace the OEM ones without going the noisy test pipe route? Or are there test pipes that don't make the exhaust tone so obnoxious

As someone on the other side of the world with a b 8.5 S4, I can confirm everything you said is 100% correct. FYI gutted cats and the 034 X pipe is a pretty good combination to not have the car sound like a straight piped Camry.

Awesome video...thanks for the loads of info

I'm guessing you have c6 experience? And this goes for the 2010 c6 model as well? Both my flex pipe, Which I just saw from your schematic, I think Come right off the catalytic converters, right? Mine just started leaking. So this is right were you said is impossible to get to, correct? So I might as well have the cats removed/gutted when I replace them?

Great video. Great explaining things.

All your videos are 100%.. thanks again

Does this apply to the newer q7s as well? I think they updated it in 2017

Great video man I'm new or new words Audi but not new to automotive in general I've had lots of vehicles 600-horsepower mustangs and GMC big block trucks etcetera but I'm getting a 30 ts5 and I definitely have some questions about the exhaust and would be great if we get touch base even for a couple minutes

i hear the rattle type noise kind of sounds like a garden sprinkler during acceleration. I cant reproduce the sound if the car is standing still and just rev it. nor is the sound present while cruising. i just hear it when accelerating and near a wall or parked cars usually make the sound more audible.. what you think would be the problem.. is it a gasket failure between turbo and catalytic converters??

Great video, but I have a question about my 2013 Audi A6 C7 3.0t. Everytime I start the car first time in the morning I get a faint smell of engine oil. Is this normal?, because it only happens in the morning and there is no oil leaks anywhere in the engine. My guess was perhaps there is a valve that vents the pressure in the engine every morning. Any ideas?.

The reason for them being so close to the engine is for emission efficiency. The faster the cats get hot, the faster they work. This is also the reason for a secondary air injector pump and the grumbly / rich start up on VAG cars. They are all added to make the CATs get hot faster.

How much at risk is a stock a6 to melting? I know that going stage 1 or 2 makes it worse but if I wanted to keep it stock besides maybe intake and exhaust do I need to remove them?

Nice video! I was about to buy a B9 S5 Sportback and now I don't know if I need to change my mind....How much do you think installing the cat. converters in the middle of the pipe lines would be? I'm interested as it would be a necessary solution (I don't like to drive slow XD)

My S4 has 72k miles and has been Stage 1 for about 3k, so I'll need to take care of this sooner than later. I saw a comment down below about removing the firewall(?) to get easier access. Do you know anyone who has done that? Maybe a video or thread somewhere?

Thank you for the info!

When I went Dual Pulley on the SQ5 I had the cats removed completely. Not only did this sound incredibly bad, but the smell from this engine without cats is truly horrible. I opted to install some Magnaflow small-profile cats into my Milltek downpipes, moving it well away from the main source of heat - and that's solved 90% of the problems. It's still a nightmare to tune the exhaust to sound decent on this engine once you've changed/removed the cats.

Not sure if you monitor older videos but I wanted to ask what you suggest for my situation (thinking maybe more options available now). 2012 A6 3.0T with dual pulley APR tune. 128k miles and stock cats/exhaust. I've been using my P3 guage to reset the P0420 code for awhile now. At this point the code comes back on the same day I reset it. I also know its probably only a matter of time before P0430 shows up next. Are there any new options for high flow cats since you made this video? I started looking at JHM but i want to keep the car either quiet or tastefully sporty sounding. I also have to be able to pass emissions.

Another great video my guy 👌🏾👌🏾 and I'm glad to hear that the worst part of this motor is just the cats!!!🙏🏾🙏🏾

I just replaced my PCV and it was ugly ontop of my valves on cyl 3 where I was getting the misfire. I’ve felt as if I been lucky at 125k and cats not showing symptoms. I wonder if there is a way to gut the cats in the car?

Hey, thanks for the info. So i had a stage 2+ tune done on my 13 A8, crank and turbo pulleys. And ever since my chech engine would come on periodically.. not too often, but the code says " catalyst system efficiency below threshold bank 1"... can you let me know if my cat needs to be replaced or o2 sensor??? Please help

Good info!

Did some research related to gutting the cats and found this potential workaround: The fault code is caused because the exhaust is flowing faster and cooler than the factory downstream O2 sensor is programmed for. Install a spark plug non fouler in the post catalytic converter O2 sensor locations. This will require you to drill the existing hole in the spark plug fouler large enough to accommodate the O2 sensor. Then install the original O2 sensor into the spark plug non fouler. In some cases this will help eliminate the fault code, but this method should only be used for off road applications as it will not meet federal emissions requirements. I saw this in a MT article related to high flow cats throwing codes in the d/s O2. There are also a couple vids for diy.

Hello, so i know everyone says because of the catalytic convert issue, to get test pipes on there. I really hate the sound test pipes make and i heard if you just gut the stock cats theres no rasp or anything, do you think gutting the cats will do the same job as test pipes? Also will i start smelling like combustion if i gut my cats?

Did you get any error code when the car went into limp mode because of the clogged cats? Thanks for the informative video!

Which o2 spacer did you purchased so we can stay away from them. Also, which do you recommend?

Mine are drilled out cats. And done a muffler delete. Sounds better than a friends with a stainless steel full exhaust system. Heard mild steel sounds better than stainless also

I have a 2016 c7.5 stock daily driven no tracking or anything, what about the oil i recently took your advice changed oil with motul 0w40 x max 100% synthetic. Its a full SAPS oil people say it can degrade and clog the cats quicker...whats your take on it? Im a fan from 🇨🇦

Great video!

Any issues with the B9 3.0T cars? We have a B9 (2019) S5 cab, and also looking in to a B8.5 SQ5 so this vid popped up. Thanks

Great vid ... I'm buying a 2010 S4 manual Tomo with extended motor plan ... Is there anything I can do without voiding my motor plan ?

Hi sorry I did not understand when you said "gut your cats, put them back in" what did you mean by this? Thanks!

I have a 2012 w/APR Stage 1 with about 76k on it. I don’t beat it but I don’t baby it. If I gut the cats won’t the lack of back pressure cause a problem? Are there O2 sensors I need to retain? If I eliminate O2 sensors won’t it effect the performance of the car? How exactly does one gut a cat? I have no emissions inspections where I live. I was considering the Magnaflow system, would that be annoying with the gutted cats and therefore I should stick with the stock exhaust? I plan to try and head this off before it happens, hence all questions. Thanks for an outstanding video!

Is this issue the same for the new I6 3.0 engines in the A7 (and others)?

I am thinking of buying a 2017 a6 3.0 with 44,000 miles. I’m pretty sure it’s completely completely stock. Should this be a worry for me I only plan on putting an exhaust on the car

At 300,000km my cat has done its job. I gutted it two weeks ago and have kept the resonator off. The muffler came of ages ago. All you need is a 45⁰ bend pipe, a metre of straight pipe to have the tip come out before the rear wheel, and some clamps. Band clamps are easy for joining pipes. My little van sounds like an old truck with the loud turbo whistle, haha

That was also helpful explaining why the welds need to be reinforced. I didn't think about that... I just knew to do it. Also, JHM relocated cats haven't had a melting issue since they've been pushed to the downpipes. There's been baffle failures due to welds though

Just had a few things replaced like water pump, thermostat, oil boot filter, pvc valve(although it did not need it at 106,000 miles) control arms for the front and shocks/struts, spark plugs, manifold gaskets and a new cold air intake. My question is, I need my catalytic converts, but I read that I could use a down pipe, then the catalytics. Can you suggest a brand and model of down pipes and cat's. I am slowly want to get my car modified, and this is the next step after my cold air intake.

Watching this video makes me close to trading in my 2013 Q5. Currently, there are multiple fault codes-stuck flap open, misfire on cylinder 3, chugging coolant, using too much engine oil

Great info, never heard of this. ( 2014 Q7 3.0t ) guess this is something I’d need address then. Also do you have a recommendation for oil catch can?

I wanted to do test pipe for so long but the fact it’s a pain in the butt job scared me away. Then the cat on bank 1 on my SQ5 finally went. Luckily the weld failed and broke off the flange before it did a lot more damage to the engine.

This video gave me some piece of mind, but left me with questions as of what to do next. I had the exact issue you described when you send it just for the epc light to come on. I checked the codes and got one for cat efficiency but just recently checked again and it said I had a misfire on cylinder 3. I’m not sure what to do from here, if I should replace the pcv or change the cats but the guy I bought it from said the cats were gutted. The pcv hadn’t been replaced yet either with the car at 130,000km What should I do from here? Change the pcv pre maturely or ignore it and chalk the issue up to bad cats?

Thank you for the info.

So I have a 2012 A6 Prestige, stage II Unitronic. My car just hit over 92k miles and on the way to work upon hitting the gas my car began shaking violently and the ECP light came on along with the engine light. I took it to the dealership, they claimed cyl 4 misfire swapped plug and coils and mis stayed in same cylinder, also cylinder 4 injector was sticking. Alon with my valve cover gaskets leaking oil. They replaced all injectors and valve cover gaskets. I picked up my car, went to work the next day and the same thing happened again! Took it back and now it’s cylinder 1 & 5 they claim it’s my coilpacks and plugs. I replaced my plugs and coilpacks 3 months ago with CTS brand so I knew that can’t be. After seeing this video do you believe it’s my cat converter causing the issue? Your opinion would be appreciated @AudiC7Owners

I think my passenger cats blew but my car is running fine is it safe to drive? I got the p0420 code and some silver dust on my tips but my car is still running really good so I’m confused as to what to do

I have an Audi a6 c8 getting a catless dp intercooler Apr intake and a weistec engineering etc and tcu tune next Tuesday so excited

this video seems like a sign. my s5 has been burning oil. not too much but every 1000 miles or so not exactly sure it’ll be down half a court. also lately i’ve been stepping on the accelerator and my car would go into limp mode and the epc light would come on. first time it happened my intake cone fell off. second time intake was fine and i started the car and the epc light was off. could this be bad catalytic converters?

It is quite normal to have cats right at the exhaust manifold, my '04 Toyota has them there and the '01 Golf also. Really nothing to be surprised about... This isn't the late 80s any more with them a few feet from the exhaust ports.

Thank you very much for this video!