mitaka

My car has been pretty much trouble-free since I got it back into thousand 12 almost nothing for 3 years. A couple of months ago I bought extended warranty wondering if it was the right decision maker has been pretty much completely trouble-free. Last week check engine light comes on. I bring it in and it turns out it's an issue with the catalytic converter and a misfire. Service advisor claiming that they had to open a case with Mercedes-Benz for the repair since this shouldn't happen at 51,000 miles.

GoBlando

Yikes, sounds like carbon buildup. Catalytic Converter = Emissions = 8yr/80k mile warranty in US.

More Detail: Carbon Buildup is a common problem with US gasoline and Direct Injected engines. This carbon builds up, and over time a piece of it can end up in the exhaust and land on the catalytic converter on its journey. The engine experiences misfires because a piece of carbon prevents a good seal. I had this happen on my last car twice. The first time happened around 51k. It actually took out 2 of the 4 catalytic converters on that car. They ended up doing a manual cleaning of the intake after replacing the catalytic converters. There is no way to fully protect against it at this time.

GoBlando

Any word from the dealer?

mleskovar

This is true until we get Euro spec gas but you can help minimize it by waiting for the motor to come up to temperature before opening up the throttle and even when at temperature not stomping on it at low revs. Keeping it in the "S" trans mode helps DI gas engines have been around for years so you would think something would have been done about this problem by now for US customers

Trancebolt

I bought my C300 luxury 2010 from one of my dads customers. They babied the hell out of the thing, and who knows if the guys son used it and put cheap gas in...

Low and behold, mid 2013. I tell my dad of certain sounds and what not.

Turned out to be BOTH catalytic converters and some shock related issues, oh yeah and exhaust.

Bottom line, it happened at 33k miles. The dealer is trying to buffalo you. Any catalytic converter issue is under warranty. 51000 is RIGHT outside of initial warranty, but with that extended and it being JUST on the cusp, they should honor the fix immediately.

Terrible thing to happen at 1,000 miles over warranty. Striking how often things break right after the warranties engineering run out period. Had this happen on an acura RIGHT at 100k. Curious ay?

Arrie

DI engine carbon buildup issues are related to the intake valves. This is because the fuel with cleaner additives does never flow thru the intake valves. Being a DI engine has nothing to do with catalytic converter problems.


Carbon buildup in the exhaust side then normally means the engine does not burn all of the fuel it is given. Problems with the converter at the same time of misfire would actually tell reason for the converter issues, i.e. the converter is failing due to improperly burned fuel that is a result of misfire. It does not tell if you have a spark problem or a valve problem though.


Valve not closing properly could be a buildup issue.


Spark could be lost or partially lost by number of reasons simplest being the spark plug itself.

mitaka

OK here is the update. All work was covered by my extended warranty. I waited more than an month for the catalytic converters to come from Germany. I had a brand new ML loaner so no complaints about the long wait. I was seriously considering not to buy extended warranty but thanks to this forum I got an amazing deal so I did pull the trigger back in December. Two cat converters replaced 212-490-29-47 and 212-490-30-47 plus some clamps and bolts. The parts above alone are $1400/1500 each and everything was covered by the extended warranty. I just do not understand why these cats went bad at 50K. Bad gas? I use mostly BP

Trancebolt

Well, my 2010 non direct injected, had a catalytic replacement at around 40,000. Got it CPO from my dads old customer, and hes a rich old guy who barely drove it (although drove it into potholes alot, thanks alot... just cuz somethings not driven hard/alot doesnt mean it wasnt driven carelessly)

Now, he couldve lent it to his son who filled a tank or two of 85..hes hard on his cars i know cause my dads mechanic takes care of all their stuff. i mean, my girls mom took the car for a trip and she filled up half a tank of unleaded... i was like 0_0 and that was like two months ago.

Mercedes specs the car for 98... we max at 95. unless your putting in special 10 dollar a gallon stuff. So even at 95 the cars barely happy. Also they limit the power output on cheaper gas. Not a good thing at all. Combination of that and late oil changes or cheaply done oil adding... Take your pick.

Maybe someone you know put a few tanks of it in. Happened under my nose plenty of times, and im not sAYING thats why my cat failed.... but it did. That car wasnt crashed or anything so its likely corrosion or buildup. damn

glad you got taken care of mate.

Johnny Rad

Those aren't directly comparable as the European octane rating is measured differently than N. American. The Euro RON 98 is equiv to North American 93.

Therefore, it's misleading to say our North American Mercs are designed for 98 octane without specifiying which octane rating.

https://mbworld.org/forums/e-class-w...50-octane.html

http://www.pencilgeek.org/2009/05/oc...nversions.html

http://oldeloohuis.com/octane.html

noka

Wouldn't the emissions warranty have covered it?