cats gone bad

[Kprad12]

My cats have gone bad at 70,000 miles on my m37. At first I thought it was the transmission which I had recently gotten replaced under warranty but after a dealer diagnostics for 180 bucks they said it was the cat. Sadly they are quoting 1,300 to replace and I live in sunny California which has super strict emissions . 1,300 is a lot to swallow especially after purchasing a M4 so I was looking into other options. Not sure what I am going to do at this point I have no idea how they could have gone bad this early but I'm thinking about deleting the cats and faking out the emissions guy by using the old trick of cutting the cat in half and welding it around the exhaust. They no longer use sniffers so this will probably work but I was wondering if you guys had any input?

[EdBwoy]

What year M37?
You might fall under the federal emissions warranty - 8 years or 80,000 miles; whichever comes first.

[Kprad12]

What year M37?
You might fall under the federal emissions warranty - 8 years or 80,000 miles; whichever comes first.

Hmm never heard of this mine is a 2012 I will definitely look into it thanks so much.

[amc49]

If they simply hook up to your OBD for emissions instead of tailpipe testing they will find the missing cats pretty quick, the after cat O2 sensor tells on you by showing incorrect readings. It should set a MIL as well and they won't pass it like that. The modern electronics replace sniffers, often not needed at all. You need some sort of faked output from the downstream O2 to satisfy the ECM that all is correct.

[armybrat]

What year M37?
You might fall under the federal emissions warranty - 8 years or 80,000 miles; whichever comes first.

Hmm never heard of this mine is a 2012 I will definitely look into it thanks so much.

Yep I had a cat replaced this way on my 2007 Acura MDX about 4 years ago. You're lucky - M37 cat is easy to replace vs M56 if for some reason you choose to DIY.

[AlabamaDan]

I'm not even sure what the cats do. Emissions or something right?

[Ilya]

My cats on my M56 (which is a 3k job) are acting up. The CEL only comes on when it gets cooler so luckily last week was in the 80's again and my light was off and I quickly got my car inspected. My mechanic that inspects my car every year suggested I try 'cataclean' product. I'll give it a whirl but I bought myself at least a year.

@AlabamaDan...from what I understand cats have a honeycomb inside that takes exhaust gas and 'cleans' it to reduce pollutants.

[EdBwoy]

...My mechanic that inspects my car every year suggested I try 'cataclean' product. I'll give it a whirl but I bought myself at least a year...

I'd give it a try sooner rather than later, so you're not left scrambling for options at the end of the year if it doesn't work.
... And also to save your cats from a year of wear, in case the cataclean really works.

[EdBwoy]

The following post isn't directed to anyone in particular, but I know some of our cars are getting to the age where catalytic converters are starting to have issues.
I believe we all have a duty to give the full picture when talking about such things. Sometimes saving money shouldn't be the only goal of a forum; especially one as far-reaching and authoritative as Nicoclub.

... deleting the cats and faking out the emissions guy by using the old trick of cutting the cat in half and welding it around the exhaust. They no longer use sniffers so this will probably work but I was wondering if you guys had any input?

... The modern electronics replace sniffers, often not needed at all. You need some sort of faked output from the downstream O2 to satisfy the ECM that all is correct.

The following is like me saying that most people die when you stab a knife into their hearts, and simultaneously recommending that you don't do it.
Told you how people do it, but not advocating for you to do it as well.

With regards to bypass replacing cats, I am not giving advice, but rather informing how it's done.
To build on what amc49 has referenced above, the secondary oxygen sensors give readings that when compared to those from the primary sensors, will tell you the health of the catalyst.
The primary/upstream oxygen sensor readings are constantly fluctuating with varying air/fuel ratios. When the catalyst is functioning properly, the downstream sensor readings are steady while the upstream ones still fluctuate.
When the catalyst isn't functioning properly (either missing or inefficient), the downstream sensor will provide fluctuating values like the upstream one. Each manufacturer has their own ranges to trigger a code, but generally that is the secondary o2 sensor saying, "Hey, I am seeing the same values as the primary o2 sensor! The catalyst is supposed to clean things up so I get a steady reading. Is the catalyst still there?" Then your car throws a P0420 or P0430 code.

What some people do to mask catalyst issues is install o2 simulators or anti-foulers at the downstream sensor location. There are different ways to achieve this outcome. These basically allow the secondary sensors to give false readings and fool the ECU to receive a non-fluctuating reading; hence a thumbs up for a healthy catalytic converter.

What gets people sometimes is this:
They see the cost of replacing a catalytic converter (sometimes ridiculously expensive) and think that replacing the cheaper, more accessible oxygen sensor will fix the problem.
The truth is that the o2 sensor can foul too; but they have their own codes. If you only have catalyst-specific codes, then every other sensor is doing its job and the cat is bad.
It's a matter of economy, and whether you want to spend a lot of money now or a little now then a lot later. I have advised people with P0420/P0430 codes who chose to replace the oxygen sensors instead of spending the $900 or whatever quoted for the cats. $300 later after parts and labor, the codes come right back and they have to make the decision again...or you know, some just spend a hundred bucks to fool the car and it has no idea the catalyst is still bad, so the CEL goes off and it's business as usual.

Caveat
That is a valid solution if you are lucky in the way the car gets its readings. Some cars don't work with o2 simulators. I have no info for the 2011+ Infiniti M models.

**********************************************************
With that out of the way:
There are legal, ethical and moral issues that go with such a move of intentionally fooling emissions control equipment. Again, not judging, just informing. Above all that, there are health concerns in running a car without emission control equipment.

If you are in the position to, stand next to (or even sit inside) a straight-piped vehicle versus a similar one with all catalysts present and operational.
You should smell the difference in the vehicles while they are idling from outside and sometimes while inside the vehicle. And that's just the stuff you can perceive. A lot of harmful substances are invisible and odorless. Have you ever run a car inside a garage for long enough, even with the door partially open, and stood inside the same garage for over 10 minutes?

I am not even talking about the environment. For the sake of the people around you and yourself, that is something to consider.

[Ilya]

...My mechanic that inspects my car every year suggested I try 'cataclean' product. I'll give it a whirl but I bought myself at least a year...

I'd give it a try sooner rather than later, so you're not left scrambling for options at the end of the year if it doesn't work.
... And also to save your cats from a year of wear, in case the cataclean really works.

Yeah I plan to in a few days when my gas tank is at the sufficient level per their instructions.

[armybrat]

My cats on my M56 (which is a 3k job) are acting up. The CEL only comes on when it gets cooler so luckily last week was in the 80's again and my light was off and I quickly got my car inspected. My mechanic that inspects my car every year suggested I try 'cataclean' product. I'll give it a whirl but I bought myself at least a year.

@AlabamaDan...from what I understand cats have a honeycomb inside that takes exhaust gas and 'cleans' it to reduce pollutants.

I actually pulled a P0420 code on Aug 29th, driver's side cat efficiency below threshold. What's funny is that the threshold is like 3% from 100% efficiency. It's so low that it's worth trying alternative methods of reducing that number, and a lot of times a simple cleaning product like Cataclean will do the job. With that said, I used the Cataclean, as instructed, and my light went out, and hasn't popped back up since. Passed NC emissions last week. You have to put it in with about 1/4 tank of gas, and drive it around for 15 - 20 miles before filling up the tank. That is very important. Don't add it to a full tank.

[Mjkkb2]

Thumbs UP for very educational post...Thank you

[satown210]

Something else about when a catalytic converter go bad. Nissan came out starting around the 3.5 engine with a new feature to help emmisions. During the intake cycle, there is a brief moment of valve overlap where a small amount of exhaust is drawn into the cylinders. This is to ensure a total burn and re-burn for cleaner exhaust. If the catalytic converter is failing and breaking apart, ceramic material can get into the cylinder. This will score the cylinder walls resulting in lost compression and oil consumption. Nissan were bad about this due to how close the cats sat to the engine. Most manufactuers have the same valve overlap feature in their engines.

We got quite a few Maximas, Muranos, and Altimas in the shop with low compression, blowing smoke, running poor. Every story was the same, they had a check engine light for a cat and kept driving it for quite a while.

[Ilya]

My cats on my M56 (which is a 3k job) are acting up. The CEL only comes on when it gets cooler so luckily last week was in the 80's again and my light was off and I quickly got my car inspected. My mechanic that inspects my car every year suggested I try 'cataclean' product. I'll give it a whirl but I bought myself at least a year.

@AlabamaDan...from what I understand cats have a honeycomb inside that takes exhaust gas and 'cleans' it to reduce pollutants.

I actually pulled a P0420 code on Aug 29th, driver's side cat efficiency below threshold. What's funny is that the threshold is like 3% from 100% efficiency. It's so low that it's worth trying alternative methods of reducing that number, and a lot of times a simple cleaning product like Cataclean will do the job. With that said, I used the Cataclean, as instructed, and my light went out, and hasn't popped back up since. Passed NC emissions last week. You have to put it in with about 1/4 tank of gas, and drive it around for 15 - 20 miles before filling up the tank. That is very important. Don't add it to a full tank.

Yep, same code as me lol. And correct on the 1/4 tank, that's what I'm waiting for (I work from home though so I don't go through tanks as quick as I used to).

[ssmrico]

has anyone done the high flow ones they sell for these cars? or maybe even gut them?

[EdBwoy]

Thanks Mjkkb2. As wordy as that was, it's just a summary covering the basics of emissions systems. You could spend a month immersed in the details of closed loop feedback.

...(I work from home though so I don't go through tanks as quick as I used to).

Not a bad problem to have at all, hehe. I envy you

[biggie]

I assume the cats are different from V6 to V8. If/when mine go out I hope to find some HFC for the 5.6L. I know there is a company that makes them for Armada/QX56/QX80 in Louisiana, hoping they can have something for the M56.

[armybrat]

I assume the cats are different from V6 to V8. If/when mine go out I hope to find some HFC for the 5.6L. I know there is a company that makes them for Armada/QX56/QX80 in Louisiana, hoping they can have something for the M56.

They are. The V6 cats bolt on to the exhaust manifolds. The V8 cats ARE the exhaust manifolds. The QX56/80 and the M56/Q70 5.6 exhausts are pretty much set up the same way up front, except the QX secondary cats bolt between the exhaust manifolds and the Y-pipe assembly, while the sedan 5.6 secondary cats are welded to the Y-pipe assembly. The "HFC" you're referring to for the QX56/80 replaces the bolt on secondary cats, not the main primary exhaust manifolds (main cats).

Behind the Y-pipe, the sedan has dual resonators going to dual mufflers. The QX doesn't have resonators; from the Y, it's a single pipe going into a main muffler, then to a single secondary post muffler/tailpipe.

[vr4z06gt]

My cats have gone bad at 70,000 miles on my m37. At first I thought it was the transmission which I had recently gotten replaced under warranty but after a dealer diagnostics for 180 bucks they said it was the cat. Sadly they are quoting 1,300 to replace and I live in sunny California which has super strict emissions . 1,300 is a lot to swallow especially after purchasing a M4 so I was looking into other options. Not sure what I am going to do at this point I have no idea how they could have gone bad this early but I'm thinking about deleting the cats and faking out the emissions guy by using the old trick of cutting the cat in half and welding it around the exhaust. They no longer use sniffers so this will probably work but I was wondering if you guys had any input?

Can you explain your transmission issue? I am also having what I believe is a transmission issue, shudder/vibration under light load (doesn't happen in first, but very noticeable in 2nd and 3rd). Dealer first told me it was winter tires, then they replaced the valve body, and finally they sea foamed the engine. Nothing has resolved the issue so I am curious what your experience has been. I still have power train warranty left so I am pressing to get this resolved.

[Kprad12]

Here is a link to the thread on my transmission. post6754217.html#p6754217
My Cats have not thrown me any codes I was concerned after hearing a very noticeable clicking noise at idle because I thought it was my transmission. No idea when my cats will completely fail and throw up codes but i'm assuming they're clogged right now and must be restricting some exhaust flow which can't be good for the car. My emissions test was done this year but I will try and get my car to fail (first time anyone has said that lol) so I can try out that federal warranty.

[armybrat]

Here is a link to the thread on my transmission. post6754217.html#p6754217
My Cats have not thrown me any codes I was concerned after hearing a very noticeable clicking noise at idle because I thought it was my transmission. No idea when my cats will completely fail and throw up codes but i'm assuming they're clogged right now and must be restricting some exhaust flow which can't be good for the car. My emissions test was done this year but I will try and get my car to fail (first time anyone has said that lol) so I can try out that federal warranty.

If you are able and have the time, M37 cats are a DIY yourself project. They just bolt on to the manifold, and are accessible from underneath the car. As a matter of fact, you can remove them and have a look see at the catalyst material. You may even be able to clean them. If not, Ebay, Amazon, etc. has several replacement options, way cheaper than dealer IMHO.

[Larz]

There IS another option. You can still get OEM parts and save $$$ by purchasing them from infnitipartsonline.com and have the dealer do the install. Here was my experience a few months back on my 2009 M35:

The dealer estimate was $1235 for left CAT and $825 for right CAT + $980 for labor.
TOTAL COST = $3050 !!!

I went to Infiniti parts online and paid $835 left and $693 right plus $71 shipping. They came with new gaskets, bolts, etc so very dealer parts needed.
PLUS, when I ship the old units back for a core exchange, I will get a check for$284!
The final cost for parts: $1315 (after core rebate)

My final cost including extra 'needed' parts from the dealer:

1) Some sort of "tube" that needed replacement as it was not suitable for re-use with the new CAT on the left side: $ 62.48
2) New shield locking bolts (not included with my parts, per dealer): $ 17.46
3) Miscellaneous shop charge: $27.00
Total parts charge: 106.94

Total bill for everything: $2251 (including rebate form core return)
Dealer parts and install: $3050 (no core rebate)

I saved nearly $800 by NOT getting the parts through the dealer.
Proving, once again, what dealers charge for parts + mark-up, is actually ROBBERY plain and simple!

Mind you, I could have saved hundreds more if I bought generic 'fits all' CATs.

[Kprad12]

Yeah I might go with the diy route would say I'm pretty good with mechanical stuff. I've even helped build a motor for my friends turbo build miata. Thanks might try to find some high flow cats that pass CA emissions.

[satown210]

I can't stand when people assume because they are paying more for a part, they are being ripped off. Auto repair business models rely on profit from parts and labor. There is a mark-up. Most online parts websites sell parts at the same cost as dealer and repair shops get them. I am not sure why people think they should receive wholesale pricing in a retail purchase.

Back in the old days, shops could get parts at a deep discount, upcharge them to standard over the counter prices. Not anymore. That's why there is a markup.

[armybrat]

I can't stand when people assume because they are paying more for a part, they are being ripped off. Auto repair business models rely on profit from parts and labor. There is a mark-up. Most online parts websites sell parts at the same cost as dealer and repair shops get them. I am not sure why people think they should receive wholesale pricing in a retail purchase.

Back in the old days, shops could get parts at a deep discount, upcharge them to standard over the counter prices. Not anymore. That's why there is a markup.

I don't think wholesale vs retail pricing for parts is the issue with most folks. I think the general consensus among us DIY'ers is that you're going to pay more for parts (and labor) at a dealership. For us, it doesn't make sense to buy your parts at a dealership when you can get the same parts online for up to 40% off. On the flip side, I've gone to the parts counter to get some miscellaneous OEM fasteners and push pins, and they just give them to me instead of charging me for them.

[armybrat]

In case you want to know what M56 cats look like:
Driver's side


Passenger side:

[satown210]

I can't stand when people assume because they are paying more for a part, they are being ripped off. Auto repair business models rely on profit from parts and labor. There is a mark-up. Most online parts websites sell parts at the same cost as dealer and repair shops get them. I am not sure why people think they should receive wholesale pricing in a retail purchase.

Back in the old days, shops could get parts at a deep discount, upcharge them to standard over the counter prices. Not anymore. That's why there is a markup.

I don't think wholesale vs retail pricing for parts is the issue with most folks. I think the general consensus among us DIY'ers is that you're going to pay more for parts (and labor) at a dealership. For us, it doesn't make sense to buy your parts at a dealership when you can get the same parts online for up to 40% off. On the flip side, I've gone to the parts counter to get some miscellaneous OEM fasteners and push pins, and they just give them to me instead of charging me for them.

I work in auto repair and all the time customers go, "well I can the part off ebay or autozone for $xx.xx amount you are ripping me off by charging more!" Customers constantly think that we should charge them the cheapest price they can find online. The other problem is customers bringing in their own parts. There is a profit margin we need to meet to make the job worth while. SInce we do make some money off the part, when the customer wants to provide the part, the job is no longer profitable. The other problem is most customers find the cheapest chinese no name part they can. Everytime we have installed customer parts we tell them there is no warranty since it isn't our part. Everytime, the customer's cheap crappy part fails a day, week, or month later. Customer comes back and demands we repair, remove, swap the part for free.

[armybrat]

I work in auto repair and all the time customers go, "well I can the part off ebay or autozone for $xx.xx amount you are ripping me off by charging more!" Customers constantly think that we should charge them the cheapest price they can find online. The other problem is customers bringing in their own parts. There is a profit margin we need to meet to make the job worth while. SInce we do make some money off the part, when the customer wants to provide the part, the job is no longer profitable. The other problem is most customers find the cheapest chinese no name part they can. Everytime we have installed customer parts we tell them there is no warranty since it isn't our part. Everytime, the customer's cheap crappy part fails a day, week, or month later. Customer comes back and demands we repair, remove, swap the part for free.

I don't work in auto repair, so I can't speak from that side of the equation. I am speaking strictly from a DIY point of view. As for customers bringing in their own parts, you mentioned that you have installed customer supplied parts, so that tells me that you're making some profit, even though it's not as much as if you supplied the parts...when you say "our parts", are you talking about OEM parts or aftermarket parts from your vendor? I can understand the frustration if your business uses OEM parts vs customer supplied cheaper aftermarket parts. If your policy is to use OEM parts and they want you to install aftermarket parts, then you should refuse to do the work if the part comes back defective. If the customer supplies the same parts that you use, then I don't see the problem with warranty work if you choose to accept the job.

[Larz]

I can't stand when people assume because they are paying more for a part, they are being ripped off. Auto repair business models rely on profit from parts and labor. There is a mark-up. Most online parts websites sell parts at the same cost as dealer and repair shops get them. I am not sure why people think they should receive wholesale pricing in a retail purchase.

Back in the old days, shops could get parts at a deep discount, upcharge them to standard over the counter prices. Not anymore. That's why there is a markup.

Let's all agree that unless a business can make a profit, it ceases to stay IN business.
However, when the dealer quotes me over $2000 for parts and an online Infiniti parts company (who also has a mark-up) will sell the same OEM part numbers to me for $1,300 it's more than a mark up. I don't think the dealer sets out to specifically 'rip off' anyone. But I consider their $700 mark-up to be excessively high.
If Infinitipartsonline can make a profit at $1300, the actual cost is likely close to $1000 - possibly less. That means the dealer didn't mark it up - they DOUBLED it.

[cliffyk]

If they simply hook up to your OBD for emissions instead of tailpipe testing they will find the missing cats pretty quick, the after cat O2 sensor tells on you by showing incorrect readings. It should set a MIL as well and they won't pass it like that. The modern electronics replace sniffers, often not needed at all. You need some sort of faked output from the downstream O2 to satisfy the ECM that all is correct.

This is all quite correct, the DTC that will be thrown is P1000 (OBD (On Board Diagnostic) System Readiness Test Not Complete), and that is an immediate emissions test fail; 10-15 years ago it was possible to trick the ECU into believing the cats were OK by using an O2 MIL Eliminator--a simple RC filter circuit) in series with the rear O2 sensor.

Back then we did this all the time on Mustangs an MIatas--but as the systems have become more sophisticated they are not so easily tricked as explained on my webpage...