So a month ago my check engine light came on, I brought it in to have it looked at and get service B (18,500 miles on a 2009 C63). They reset the code and said it came back saying "fuel too lean". They asked if I use premium fuel (wanted to slap the guy) and then said I could have gotten some bad fuel and for the next couple of tanks to use a different station. I was using Citgo for the last two years, so I went to BP instead. two full tanks and the light is still on, car was also vibrating at idle more than normal during this whole time AND the worst part is my gas mileage went from an average of 15.5-16 MPG to 11 MPG, driving even more conservative than normal, so something was diffenetly wrong.

I take it back and the same code comes up, fuel too lean, I tell him its impossible unless all of Chicago has bad fuel. And I have read that certain things can make the fuel lean (purge valve issue). I told the dealer about a thread on here about the purge valve maybe needed to be replaced. his response was on any AMG cars under warranty they have to follow strict Mercedes protocal for fixing them, they have to notify Mercedes of the problem wait for a response and only do what Mercedes tells them, then report back if it worked or not. He said they do this to avoid the same issue with future owners... Well I brought the car in 8 days ago, because of the holiday weekend they didn't do anything for the first 5 days, then they order a new fuel modular and install that, problem not fixed, so they call me today and say Mercedes now wants to try replacing the INTAKE MANIFOLD! still nothing about the purge valve. He tells me that Monday will be the earliest this will be done, so that means almost two weeks without the car! Now I wouldn't mind if they gave me something just as nice to drive, even an E class, but they gave me a C300, which has half the power and sorry for any C300 owners out there, but crappy seats and suspension, plus gas mileage is crappy for a 228 horsepower car, only is getting 20 MPG, I was expecting BMW 3 series 25 MPG out of it. Enough with the loaner though, an issue that I thought would be simple is turning out to be a nightmare and of course since its over a year old, no lemon law, does anyone know if something like this shows up on a carfax? so Mercedes having no clue how to fix something will effect the value of my car when I sell it?

The new V8 TT AMGs look great, but I might have to go to Audi or BMW again after this experience.

 

who is the dealership can i ask?

 

Are you using 91 or 93 octane. I don't know what is available in Chicago.

Perhaps checking the product number on the purge valve. You can compare to the supposedly newer ones.

Purge valve replacemet did the trick for me, but who knows what's really going on.

 

We have 93 octane in Chicago.
I'm as curious as Zephyr. Who's the dealer?
I had a similar experience with a dealership in the chicagoland who cleared a Check Engine light for me and said the problem was fixed. Well a few days later it came back on and I havent brought it back yet, because the light cleared itself a few days later. Now i'm just waiting for the light to come back before bringing it to another dealership for inspection. Oddly enough though I had a dealership ask me to if I was using PREMIUM in my car..........Really?

 

^ Thanks for the feedback about octane.

 

There is an issue with the crankcase ventilation valve on the back of the intake getting a vacuum leak in it. It requires the intake to be removed. There is a bulletin on this. Until recently it was not available separately. It is not that big of a deal.

 

I don't understand. A CEL triggers a code on the scanner and that code is very specific. I am not an expert but I personnally have a scanner and I typically find exactly what the problem is on other cars.

 

Lean adaptations is the code. An adaptation code can be caused by everything from a vacuum leak to low fuel pressure to an injector, o2 sensor. air mass sensors. etc... This type of fault code is not for a specific part. There are thousands of fault codes in engine management for components and for logic chain failures. Most of the time when the check engine light comes on it is a logic chain code. Like a purge fault or a adaptation issue.

 

OK. So if the a Mercedes dealer with their "trained and certified" technician and their "sophisticated" equipment diagnosis can't figure it out what is next?"

 

MBZ and Porsche are so **** about warranty repairs. They seem to think either their dealer is scamming them or the owner of the car is. If your leasing the car, hit them up for a lack of use reimbursement for the time it's in the shop (ie they pay you the prorated lease payment for the down time). Don't laugh, it been done successfully here at a Porsche dealer I will leave un-named.

 

That should quicken their pace lol.

 

OK. So if the a Mercedes dealer with their "trained and certified" technician and their "sophisticated" equipment diagnosis can't figure it out what is next?"

I happen to be a trained and certified technician and use sophisticated diagnosis equipment every day. The simple fact is that problems are often not a current issue. It is an intermittent issue. It is very hard to guess what is wrong with a car for a problem that is not current. Adaptations many times change quickly. Even some issues that we can verify at the shop come and go so quickly there is no time to diagnose. Mercedes also only tells us what they think we need to know in order to fix cars. That is often very lacking. These are very sophisticated systems that monitor and control things at tolerances that seem impossible sometimes. We have to learn what causes issues as new products come out. For instance years ago when we had p0170-173 adaptation issues in the late '90's we did not know at first that this was almost always caused by the air mass sensors. It took time to come to this conclusion. The purge valve issue on the new c class is also a good example. This is hardly ever a current fault when it comes in the dealership. It takes trained and certified technicians to figure these things out. The fault code does not say bad purge valve. It says purge malfunction. Or adaptations. Or a misfire code. I have seen 6.3 amgs running so rough that you thought it was broken and no codes and the purge valve was the issue. Then a minute later ran perfect. It just is not always easy but we almost always find it.

 

93 is pretty standard in Chicago and thats what I use

 

I can tell you from personal experience, when I had a CEL. It turned out to be a lean condition on one of the cylinders. The culprit was the purge valve, there is a Technical Service Bulletin out of this. The problem that, I had was they just updated the software on Star. And it wasn't talking to the cars on board diagnostics. They ultimately had to wait a get another computer with the old software to adequately diagnos my issue. But it turned out to be a defective purge valve, and updated purge valve has been anotated in the TSB. Have them reference that.

 

The dealer is Naperville Mercedes, I just don't want them replacing parts that are working fine while trying to find out what the problem is, now what if those new parts go bad when the old ones would have kept working perfectly. I don't think there is anyway I will keep this car after the warranty is over, if it was already out of warranty how much would this be costing me? I would have to pay for a car rental for 1-2 weeks, pay for parts and labor of everything they do while "trying" to find the problem, this would be around $1,000 already without the issue being solved. I don't blame the dealer with this one as much as I blame Mercedes in general. I bought the car, so no lease pro-rated payment option, but they should at least give me a nicer loaner (I don't mind 1-2 days in a cheaper car, but 2 weeks!). Thinking I should just go trade it in for a S4, even trade! better gas mileage, AWD for winter, still pretty fast. Who am I kidding, once you go 450 horsepower its hard to go to anything less.

 

see this is what I don't get, a few people said there are bulletins for a few different things with lean fuel and the C63, but they have't mentioned that to me or changed anything associated with the bulletins like the purge valve. Now if they are in fact speaking with Mercedes corporate and that is the "protocal" then why aren't those the first things they try?

 

Was the coffee good there at least??

Go to MB of Hoffman Estates on Golf Road and ask for Scott Feinglass. The guy is so nice and respectful to your car and the tech Chris is excellent. Tell them I sent you. The **** C63 guy. The service is excellent, Scott is a great guy, explains everything and is on top of his game, and the the service center is clean and professional.

The coffee is also excellent...

 

actually yes, the coffee is pretty damn good!

I only go there because I bought it there and was stupid and bought a service plan for $1500 from them, before Mercedes started offering their own, so I can only get it serviced at that dealership under the plan. I realize this is a warranty issue and not service, but still took it there since I tried to be loyal. hoffman Estates is actually a lot closer for me (20 miles instead of 40) and if he can't fix it soon I will try the other dealership.

 

I had the same code a few weeks ago. Shop Foreman replaced the Tension Bolts on the Manifold as they had come loose and created a Vacuum leak. 30 min job. 1 coffee and away I went. runs better than ever.

FYI: Apparently the loosening Tension Bolts is a known issue on M156's with moderate milage on them....

 

I've been advised of this also. Not from a dealer, personally, but from a trust source who did hear same from a dealer.

 

so if they replace the entire manifold, that should solve it,

to me this sounds like a dealership milking the warranty money from Mercedes! Probably something a tech could have completed on his own but the dealership knew if they went with protocal it would mean lots more $$$ for them from mercedes.

 

There should be a sticky about issues like this and what to do to take care of this problem.


To the OP you lucky your car is stock and they not turning around to blame the tune or hardware like other members. good luck with you fix im sure it something stupid but pain in the culo for you.

 

++++++1 thanks for finally mentioning

 

Agreed. There should be a sticky on common problems with symptoms and solutions.

 

I had a similar issue with my Engine Light coming on and also was taking about 8-10 cranks to start.. Thought it was bad fuel. They replaced the battery and fuel pump with no improvement. I had the tune removed and re flashed back to stock. Car is now perfect. There must of been an issue with the software.