siklas

'07 c280
26k
check engine light, dealer says the catalytic converters need replaced.

really? seriously? anyone have this problem before?

it is under warranty, but never heard of this so soon. o2 sensor
was out the week before if that is related.

johnand

The only things that can really kill a converter is running extremely rich and being saturated with raw fuel (which causes the fuel to burn in the converter and basically melt down the internal structure), or excess engine oil or coolant entering the exhaust contaminating the converter. Also overuse of some fuel additives can cause issues as well.

You said the O2 was bad the week before. That may be the issue, but 1 week of a bad O2 sensor just doesn't seem like enough to trash the converters.

Make sure they track down and fix the problem that killed the converters, before installing new ones.

Yes, your problem is uncommon at such low mileage.

glocati

I had one of my secondary cats replaced under warranty at ~47K. I could clearly tell mine was going bad, as it rattled like a can of nails. It thought that was premature, but i did find some other members that had failure in the same approximate mileage. So, not unheard of, but 26K is weird...

On our V6 cars, there are two primary cats right after the exhaust manifolds and then they pipe down to the two secondary cats that are side by side down by the tranny.....

US Fed law is, I believe 80K - 8 year warranty on emission equipment.

Good luck on it.... Greg

MBfinatic

I had this problem last month. expensive. it should be ur secondary cats that are bad because on mine (2004 c240), there are no 02 sensors on the primary cats. maybe different for ur car tho.

acr2001

Just throwing this out there - but it's likely that your O2 sensor was fine and the dealer misdiagnosed when the original problem was actually the cat. They do love to throw parts at problems - which is just fine while you're under warranty.

W203E35

John is dead on. I have a feeling your car is running tooo rich. Explains the o2 and cat problem. I also agree with acr2001 might have been that the o2 was fine.

Also John meet acr2001, acr2001 meet John. John has also PMed me with the same question acr2001. I thing together (3 of us) we can make a great team. I got software in today so I am trying to install it. I get "You have no authorization to install the update on this system" error. 100 bucks for disk 40 Brithish pounds for the preinstall software (which I believe installs programs to imitate you already had DAS on there) and now pay another 40 pounds for them to remotely log in and find out the error is a little too much loool

Anyway more update to come

acr2001

Damn, let me know how it goes, maybe I can help you figure it out.

Glyn M Ruck

I don't know what you are trying to say?

The O2 sensors are before and after the primary and only Cats on each bank - just below the manifold. In fact on the 272 engine the O2 sensors are before the Cat and on the Cat itself between the two monoliths.

None of these cars have secondary Cats. What you call a secondary Cat is a resonator. It has nothing to do with emissions.

MBfinatic

arent there 4 cats? or am i mistaken? 2 primary in the front and 2 secondary in the back??

acr2001

Apparently it is a huge misconception that these cars (and others like the W210 E) have secondary cats. I always thought they did also. Looks like those secondary cats are indeed resonators. A lot of times a piece of the honeycomb from your cat will get stuck inside the resonator causing it to sound like a bad cat. this happened on our E class.

Glyn M Ruck

You are mistaken

MBfinatic

o. sorry.

Glyn M Ruck

Don't worry - we all learn. I was puzzled as hell when I first joined the forum & heard people talking about secondary Cats. I've learned a hell of a lot from this forum.

glocati

Apparently, I am misinformed as well. Glyn, are you saying the two cans up by the bolt labeled 70 are the cats, and the two cans down by bolt 170 are not cat converters? Thanks, Greg

Glyn M Ruck

Correct!

splinter

Can’t speak authoritatively regarding RoW configurations, by my M112 has four catalytic converters. :nix:

Glyn M Ruck

Now that opens a whole new debate? splinter does not talk crap & I'm not suggesting others do either. Really! And where is your post Cat O2 sensor to monitor effectiveness??? If I'm talking crap about American models - or any models for that matter let's get it right. Karo has checked the 272 and confirmed my comments on US models. The 272 has dual monolith Cats up front X 2. Three way in Europe which they can't be in the US with high sulphur fuel.

MBfinatic suggests that there are no O2 sensors before & after the
"primary" Cats - surely not the case????

Moviela

It thought the secondary cats were the ones you called in when the musicians you hired to score the picture were too hungover to play.

W203E35

Yup, when I checked the diagram (WIS) under "Emissions" got no pic or any documents saying anything about "Secondary Cats". When I went to "Exhaust System" I did get an image of these "Secondary Cats" but again there is no info on them to distinguish what they really are. In Exhaust it does mention the resonator and calls it silencer and it does talk about muffler but no where does the WIS document talk about these "Secondary Cats". I'm trying to wonder what is there purpose. Do they have the inside makings of a Cat or a Resonator.

I'm starting to think this was put here to create backpressure

MBfinatic

^ thats true. thats wat my friend mechanic said. i had my secondary ones go bad about a month ago.

W203E35

Have a look at this diagram.

W203E35

Karo is stupid for posting the exhaust system for the m272. Mine is the m112 so how can he compare the m272 and m112?

W203E35

By looking at these diagrams I still feel this is to create back pressure as well (not 100% sure but have a feeling). Glyn is correct as well because this thing will resonate sound.

If it really is a Secondary Cat it should atleast have some type of sensors.

More investigation being done.

W203E35

I thought this might be helpful for future problems and also help to get a better look what these "Secondary Cats" look like. Notice in all there documents nothing is mentioned about them.

Look at Picture 3 and 6.

ohlord

The pre is the small one located between the two o2 sensors on each bank the two mains have no sensors. The two small ones come to temp quicker and limit pollution faster. Unless the ops were defective something is wrong and needs to be diagnosed. Compression checks need to be done for oil blowby and also why an o2 sensor died when they last 100k.
Most often the cat death rattle comes from the main cats.Thats the big ones.
You can get magnaflow universals and splice them in if out of the 8year 80000mile warranty.Unless you are in California and magnaflow is working on getting carb approval for that one as well.