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Discussion Starter #1 (Edited)
So I'm close to fed up with our little benz. Over the past couple months we have been getting random misfires error P0302, changed plugs twice now and things got better. Ran it with a bunch of cleaner and have only used higher quality fuel.

Well now we have a whole new set of problems that just popped up. The car acts like it will not build boost under throttle, it idles fine and has decent pickup under the most minor throttle application, but forget anything close to full throttle. A bunch of new error codes came up and after clearing them, they immediately come back.

P0031 - HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
P0037 - HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
P0075 - Intake Valve Control Solenoid Circuit (Bank 1)
P0414 - Secondary Air Injection System Switching Valve A Circuit
Shorted
P0448 - Evaporative Emission Control System Vent Control
Circuit Shorted

Any ideas or maybe someone has been thru this before?

Here is some background on the car in case anyone sees the significance, 102K miles on the little sport sedan and pretty much has led a very charmed life, no issues whatsoever before this point. I replaced the valve cover gasket about a month ago because I saw a bit of oil weeping around the spark plug holes.

I've been doing a bunch of research and the only thing that comes close would be that TSB 2009100001 for the cam sensors pulling oil into the wiring, but I have not checked to see if there is oil in the connectors as of yet.
 

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Discussion Starter #2
More info.

Called to the local dealer with the VIN and they tell me the car has already had that service campaign completed on it.
 

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This really sounds like an electrical problem. Did you maybe disconnect or damage a wiring harness when working on the valve cover? I'd start at the O2 sensors and trace back to their wiring harnesses - that might give you a clue.
 

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Discussion Starter #4
No I didn't remove any of the wiring when changing the valve gasket. But I will take a look at the loom that runs across the top of the cover.
 

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Update - Wiring looms over the top of the valve cover are pristine, no leaks from the cam sensors into the wiring. Ran a compression test and here was the results:
cylinder 1 - 152, 2 - 149, 3 - 150, 4 - 150

I guess I'm off to an indy to have a diag. done
 

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Discussion Starter #6
Just an update...dealership says no way they will help out, once the campaign is closed on an issue they are done and remove any responsibility. Nevermind, all the damage was caused by the initial issue...the wiring harness is totally corrupt and damage was caused by the leaking sensors in the first place as they are no longer leaking. My endgame, replace the harness on my own dime,fix whatever else comes up after getting a true diag. and get out from under this disaster of a car. The car is great, if you don't consider the electrical/mechanical issues on such a young car. Handles great, when it runs right it really does.

I guess coming from an older W123 280TE wagon with well over a half million miles on it to this is where my expectation comes from. What a decline MB is on. Not much better then the rest of the disposable cars out there - /rant.
 

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Just an update...dealership says no way they will help out, once the campaign is closed on an issue they are done and remove any responsibility. Nevermind, all the damage was caused by the initial issue...the wiring harness is totally corrupt and damage was caused by the leaking sensors in the first place as they are no longer leaking. My endgame, replace the harness on my own dime,fix whatever else comes up after getting a true diag. and get out from under this disaster of a car. The car is great, if you don't consider the electrical/mechanical issues on such a young car. Handles great, when it runs right it really does.

I guess coming from an older W123 280TE wagon with well over a half million miles on it to this is where my expectation comes from. What a decline MB is on. Not much better then the rest of the disposable cars out there - /rant.
they replaced my engine harness under the recall...i would lay a smack down on them
 

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m54sam: please fill out your profile so we can see where you are. I assume you are in the USA? If so, go online to mbusa.com and sent them a note to request help:

Mercedes-Benz USA
 

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If it's been good to you up till now, don't necessarily give up.
If MBUSA won't help,
Lot of people have been able to clean the harness, disconnect everything that's connected to it, spray degreaser into the harness, it will drain out through the harness and take the oil with it. Let it dry.
Or you can remove it and soak it. No need to buy a new one.

Check the ECU for leakage into there. Need to clean that up before it causes ECU fail.
And it seems the only sensors that get f'd are the 02 sensors. And at 100K they were due anyway.

Would also suggest perhaps considering a new timing chain, and then you should be good for a long while!
At 100K there's probably some things you should do...
fuel filter, new trans oil, diff oil, things like that.

Good luck!

Also...maybe spray some oil all over the cam magnet? Ha...2nd failure....send pics to MBUSA. Gotta fight BS with BS some times. Take it to another dealer, and say, hey that 1st dealer doesn't know what their doing, they f'd up the service campaign, I mean look at all that OIL?!!!! And now I need a new wiring loom too. Bastards!!!
Pitting dealers against each other can work...I know. :)
Say stuff like you're looking for a new dealership to perform your future services, and
don't mention your indy. HA!!! Maybe show up in suit.
 

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Discussion Starter #11
Went to my local dealership, pretty new one to the area. They were nice up until they could not tell me what the problem was. The service manager told me I was basically SOL. They have to pull the entire thing apart to find out whats wrong. What really baffles me is that when a service campaign is done, they do not record what was replaced along with the affected parts? I had a conversation with the tech that was assigned to my car out of earshot of the service manager, he told me that it happens all the time...items are replaced and put in the wrong spot and wires are pinched and fail with time. The cam position sensors on this car go bad and will continue to go bad for the entire life of the car, no matter what they replace the parts design is flawed. MB will replace it once on their dime then its all on the consumer.

I was respectful, looked professional when I showed up and knowledgeable. It didn't matter. I looked at the service manager and asked him straight "You mean to tell me that since the campaign has already been done, whether it was done correctly or not, once it is closed there is nothing you can do to make things right?" His reply "there is nothing we can do, you will have to pay for it to be correct". I told him I was very disappointed in MB..and that they will be losing a customer/family from using their product after this is over. Not even a blink in reply from him, makes me wonder how many times a day this happens. Do they even care to take care of a long time customer when they are selling SLS's, SL63's and the likes, probably not...as my case is a drop in the bucket when compared to those price tags. Kind of sobering weekend...
 

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Ours has started throwing error codes and check engine. Don't know what they are. Lat time it was at the dealer they tore it apart and found nothing, but were able to confirm that the engine is running like a champ. Not sure what to do next.
 

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Discussion Starter #13
Get yourself a cheap ODBII reader and plug it in to find out what kind of codes the car is reporting as a start. Mine started misfiring but I wouldn't have been able to tell it was unless the codes started showing up. Still ran great thru all the misfires.
 

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Get yourself a cheap ODBII reader and plug it in to find out what kind of codes the car is reporting as a start. Mine started misfiring but I wouldn't have been able to tell it was unless the codes started showing up. Still ran great thru all the misfires.
Where would I find such a reader?
 

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Most auto parts stores carry them, and Sears, Amazon, etc. Amazon has several for under $20. Another alternative is to visit your local AutoZone or similar chain parts store - many of them have a scanner and will read OBDII codes for free.

Keep in mind that these generic OBDII code readers only scan the ECU (which is what will trigger your MIL illumination). They won't scan the car's other systems like ABS, SRS, transmission, etc. Also, MBZ shop equipment can sometimes read more discrete, specific ECU codes where the OBDII "P" codes may be more generic. Still, for $20 or so, a generic scanner is a good investment when your MIL is illuminated.
 

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Discussion Starter #16
Most auto parts stores carry them, and Sears, Amazon, etc. Amazon has several for under $20. Another alternative is to visit your local AutoZone or similar chain parts store - many of them have a scanner and will read OBDII codes for free.

Keep in mind that these generic OBDII code readers only scan the ECU (which is what will trigger your MIL illumination). They won't scan the car's other systems like ABS, SRS, transmission, etc. Also, MBZ shop equipment can sometimes read more discrete, specific ECU codes where the OBDII "P" codes may be more generic. Still, for $20 or so, a generic scanner is a good investment when your MIL is illuminated.
Thank you for responding, I didn't check the thread again since my last post.

Update: So the car is at the independent shop owned by a very trusted friend. We bought a replacement harness for the car as a first thing to replace in order to get rid of all the electrical ground fault errors, and to hopefully trace the issues down. First thing he saw when removing all the components needed to replace the wiring was that the main harness was smashed in a places underneath the supercharger. He said the only time anyone would be under there was to service something such as he was doing. The car has "only" been at the MB dealerships. Granted I can't really take that info to the dealership now since I have it at an indy now but it's really frustrating. Still have to vent some more, and I will update as info. comes.
 

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Discussion Starter #17 (Edited)
Another update, wiring harness was crushed in two major spots on top of the valve cover and underneath the supercharger. Replaced the harness, error codes are still coming up. ECU looks like it got fried from the shorts to ground. Awesome work unknown MB dealership! I say unknown MB dealership because MB won't tell me who did the original TSB's. Which is the only time anyone would have the supercharger off and had the ability to crush the wiring.
 

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Discussion Starter #18
So, we found out which dealership did the TSB where the original harness was replaced at. Went to go speak with the service manager, with all my paperwork and receipts from the independent shop that found the crushed harness.

The SM scheduled a checkup on the car for Monday, we dropped the car off and they replaced everything that was needed to make it right. We picked the car up last night and spoke with him about how our faith in Mercedes Benz was shaken, we are both enthusiasts, follow F1 closely and have both owned Mercedes Benz cars most of our lives.

This is the part where I have to say the service manager really represented MB well and did what he needed to do. They danced around admitting fault many times but paid for all the work. MB is now re-reimbursing my cost of the harness I replaced at the independent shop. So, in the end I'm glad I held my ground, glad I didn't try to play the system by putting oil in the wires. Well done Mercedes-Benz, I may have to reconsider my moving to another brand.

*the names of the dealerships have been intentionally left out, they deserve that in that they made the situation right. If anyone really wants to know the name you are welcome to ask me via PM as I would recommend them to anyone for honest work.
 
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