WIth a plethora of sensors in the exhaust, exhaust back pressure/pressure differential how could they not have seen this at first. Also I'm curious what Pico test they have performed. Mb technical support is only as good as the technician diagnosing the problem. Can't you try and ask for the quick test report from the dealer?
Edit: M157 has no pressure sensors in the exhaust🥲

 

Catalysts fail due to being fed the results of misfires. The air and fuel not burned in the combustion chamber WILL burn in the cat and will add a LOT of heat to it, melting one or both cats. Cats don’t just up and die as they did in the bad old days (1970s-80s).

 

Agree, that could be the issue but at this stage MB is not saying they are bad, only "out of spec". Not yet sure till after xmas what they come up with. Last time I saw my car was 10/6/23. Hope they sort it out before New Years.

 

I should have said in my last post that the Svc Mgr told me that MB replaced one of the Cats about the time they bought back the car from the previous owner at around 14K miles. He said they were now going to do musical chairs with the injectors to see if they get misfires when moving a known troubled cylinder's injector to a new spot and vice versa. Given everything else they replaced, and having been in there once already, seems like they would have just replaced them all, but apparently not.

 

Considering they have been spending YOUR money one would think they would have offered you the opportunity to replace all eight injectors.

 

Happy New Year! Car still at dealer. Yesterday's message from Service Manager is that Germany says to replace Gas Tank because of contaminants ( first I have heard of this one ), and that there is a kinked hose going to a fuel pump. Says the bill would rise to over $28,000 if they proceed but the MB Rep is telling them not to proceed until upper management somewhere in MB weighs in. Imagine taking your car to the dealer with a Check Engine Light and waiting three months for that news! They requested $5000 a month ago as they were throwing darts which I paid in good faith. The way I see it is that MB has responsibility for this debacle since they bought the car back from the previous owner and presumably fixed it before selling it to the outfit I bought it from. I had the selling entity ( reputable company that sells buybacks ) take it to a MB dealer for a PPI which I paid for and the car was declared to be perfectly fine. It literally looked and drove as new, with 14K on the clock. The explanation at the time for why it was bought back was that there was some minor software update needed and folks take advantage of Lemon Laws in CA all the time. As I recall, it had remaining warranty from MB and also from the selling entity when I bought it but that expired due to time by now. I've only put 6K miles on it in three years! So we will see what MB comes up with next. I'm open to trading it in with them but they have said they can't do anything on that front until they know what's wrong with it. I suggested dropping a new engine in and that would certainly fix the CEL -- but this gas tank and kinked hose is a new wrinkle. Oh yeah, they also want the dealer to put in all new injectors too. Obviously going to have to get a lawyer involved unless MB does the right thing by me. I doubt they need this crazy story out on social media and such. SMH!

 

Good Morning Quadcam,

I've mentioned your story to our shop foreman here at my dealership. We have an E63s that we've replaced full pumps, injectors, fuel rails, engine control module. All at the hands of Mercedes telling us to replace parts according to them.
My shop foreman just ran to me to let you know, double check the main body ground, went from the transmission bell housing to the body. Ours was corroded and needed attention ASAP. foreman has cleaned that up and already completed his AMG test. Currently producing CAT efficiency codes now.

Maybe this helps..
we have had this car for over a year regarding performance issues

 

Thanks C43, curious what year yours is. Assume it is same engine? MB Germany wants the gas tank and all fuel injectors replaced now. They say the tank has contaminants in it. Good news is that MB has agreed to pay all labor cost for this fiasco. I'm still stuck with paying for all the parts that were exchanged for new, most of which were perfectly fine I think. Those included ECU, Fuel Rails, Coils, some Injectors etc.. They are convinced mine is a fuel contamination issue and they previously checked all grounds. We will see in a couple of days after they replace the tank and injectors. I appreciate that they are covering the labor costs, but still feel salty about all the parts that they say were necessary to replace in order to assess what the issue was. Clearly it is a buyer beware on Mercedes cars IMO if they are not under warranty because the CEL does not reveal to the Dealer what the heck is the problem. I may get rid of the car after it is declared fit out of fear that something like this happens again, and because the car has been out of service for over three months. Additionally, the engine has been taken apart multiple times and this gas tank removal is another major surgery that requires taking the rear end apart to extract and replace.

 

I would tell the dealer you want all of the old parts. I would guess most are still fine and you can sell this stuff online to recoup some of your money if you are so inclined. Particularly the ECU. I would probably sell it at this point as you are right that a lot of stuff has been disturbed multiple times with more to come.

 

Any update on this?

 

We are almost 4 months at the Dealer now and they tell me the car is finally fixed. Mercedes NA and the Dealer worked together to significantly reduce the bill which had mushroomed to around 30K. This was for my 2018 S63 that had a Check Engine Light and misfire. Unbelievable. At the end of the saga, it was determined that the gas tank had foreign material in it and that led to problems with the injectors which were all replaced along with the gas tank. At the end of the day, they are telling me it will cost me almost 8K. I will be given no parts as MB requires that all of them be sent back to Germany as part of this deal.

How did foreign material get in the tank and what was it? Mystery.

It's been a horrible experience on a 20,000 mile car that would otherwise be an amazing machine. Now I'm wondering about keeping it. I suppose I will, since all the parts they replaced are under a two year warranty now including labor I think. If I put my foot into it again and that damn Light come on with the misfire, that will be it for me with this car.

Best to all

 

Thanks for the update. I am really surprised that the fuel filter did not catch whatever was in the tank unless it was a liquid. Weird. Glad it kinda worked out for you. Enjoy the car.