2012 e550 with oil in wiring harness
 

hmm, what would be the preventative measure to avoid this? That's not something I want to experience if there is some cheap prevention.

Not disputing this, just thinking that's strange how a leaking cam sensor can impact O2 and ECM. I guess somehow shorting out contacts? But then even the high speed bus can short to ground without necessarily ecm damage.
The sensors themselves are just plastic units with o-ring seal that plug to a harness connector, similar to dozens out there, was this an internal leak into the plug itself?
@Jon, I'd guess preventive maintenance might be new sensors if there's an updated version. Edit - I see where MB installs some sort of adapter harnesses.
Incidentally I was looking at your w212 sub install, very helpful, thanks

Yes, I'm also curious about the exact circumstances of such an issue that is common enough to have such a TSB. If it's easily accessible sensors with o-rings that deteriorate or something like that I would consider just pulling them and replacing the o-ring or sensor.

OK, since the OP is not contributing details, I decided to look up the referenced TSB, which can be viewed here:

http://www.revbase.com/BBBMotor/TSb/...dPdf?id=177389

This states that the affected engines are 272 and 273, which is the 350 engine or the N/A V8 in E550 up through 2011, so this TSB does not even apply to the OPs listed 2012 E550 with M278 biturbo engine.

Further reference to a "cam plug oil leak" issue here, which states it is only a problem affecting models up to 2008:
http://australiancar.reviews/mercedesbenz_M273.php

If your car is affected by the campaign it seems you should visit the dealer for a retrofit wiring harness adapter kit to be installed. As shown in the linked TSB pics, the sensors are just below the oil filler cap area, so watch out for any oil escaping around there.

I really don't see how you don't understand that your car has a completely new and different engine design from those affected under the TSB you are referencing. 2011 and prior E550 V8 engine is N/A 5.5L, code name M273 as referenced in the TSB. 2012 and later E550 V8 engine is Biturbo 4.7L code name M278.

So you're saying you have a 2012 E550 with a 273 engine and wiring harness from 2008?

So if you read the actual TSB you're referencing from the beginning, their fix is not to replace the sensors, so it does not matter which "batch" they were from. The fix is to simply add some retrofit wiring harness adapters, I assume to keep the oil contained or dripping down rather than running into the engine harness.

The bulletin was written Nov 2012, what is the production date on your 2012 model? Assuming they would retrofit or install an improved harness with a new engine design. Does your wiring harness connecitons look anything like the "before" pics in the bulletin, or the "after"?

So back to my original question it seems if the harness is in fact not a new design for the 278 engine the prevention step is to get ahold of one of those retrofit harnesses and install it, which is a 10 minute snap-in job.

You missed the preventative part above. Sorry about your luck. Another good reason to DIY your oil changes and have a good look around for any leaks in the process Leaking fluids should be addressed ASAP, many people let it go which leads to other problems like this. I clean my engine bay a couple of times per year and look over things. The location of this leaking would be pretty obvious in the process of an oil change.

IMO I'd give that a shot before yanking the engine.
I couldn't figure out why ECM replacement was initially called for as its located higher than the sensors. I'm not even sure why O2 sensors had to be replaced. There's 2 upstream and 2 downstream - all of them?
They may be concerned about wire harness oil degradation but why not at least try to clean the harness as reasonably possible. It will still be oily but some degreaser couldn't hurt at this point. I'd also ask to see all O2 sensor wideband readings on their scan. If they're wanky, cleaning the connectors may be a fix.
I've got a nagging feeling about what the dealer is telling you. Seems like way overkill from my limited perspective, but dealers often replace vs fix.

This is what the dealer said was the problem, right?

This is strange that it is the exact same issue as the M272, but showing up on the M278,

As MUD mentioned, I find the dealer's response to the issue strange. Although you do have to drop the exhaust on the M278 to replace the O2 sensors, I don't think you need to pull the engine.

They already cleaned the harness once... and the problems persist. I am comfortable hitting the control alt-delete.

I have obtained a sizable concession from the dealer to solve my problem in an un-compromised fashion. It's not quite the same level as outlined in the bulletin, but for me, it's close enough for horseshoes. Apparently, my argument with them, MB USA, and my service history carried some weight....

They are going to replace ALL the affected components: wiring harness, O2 sensors, ECU, and Camshaft sensors, and install new preventative pigtails, for a price at just over half of the original work order estimate. I know it's probably overkill, but given they've dried the harness once and problems persist and so I think the right course of action is a full re-boot. I've had nothing but great service from them and I trust their recommendation and respect their concession.

Besides, there is another dude with a CLS 550 from the similar born on date who took his to an independent mechanic who did the drain the harness procedure and pigtail install on the cheap... but now that guy (Rolondro) is experiencing a phantom turbo error message that so far has been impossible to pinpoint. I'm wondering if its possible its a poor signal from a half baked repair.... This uncertainty supports my decision to go with the dealer recommendation for full replacement. On the other hand, he could have bad turbos or cats.

Anyway... its all impossible to say for certain what is the best course of action. Bottom line is 1) I LOVE LOVE LOVE LOVE the TT V8 power of the E550, LOVE LOVE LOVE the e550 form factor, I love that my car massages my back as I drive, and I love getting progressively more bolstered as I pull more Gs in a turn. The car is un-compromised, and I'm happy to pay for un-compromised service to keep it in tip top shape. I'm going to roll the dice and continue on my original plan to drive it into the ground. Call me stupid in love. But whatever.

Still open to recommendations on whether I should replace the turbos while the engine is out. Car is at 96k miles. Also wondering what I should expect to pay for a swap of like for like for the turbos. It doesn't make sense that I should pay full price for turbos when given the value of remanufacturing my good ones. One the other hand, there is also something to be said for keeping TT's that have been flawless for 96k miles.... knock on wood.

One last comment before I sign off (and I'll report back one the final results)... after scouring the posts on this forum, most people here don't seem to keep their cars long enough to have a realistic opinion on actual reliability and maintenance costs. It's impossible to find for example reliable data on turbo longevity. Also, "reliability" threads seem to be packed with people boasting of things like "20k trouble free miles", or "I bought my car with 30k miles on it and am at 70k now and its as reliable as my old Honda..." What a joke. I guess what I'm starting to think is that most people wouldn't dream of owning a car like this out of warranty for the reasons I describe here. But what I hope (and believe) is that this car, properly maintained, will drive like a MB car drives, for as long as you properly maintain it. In other words, it's not a disposable box of metal, but rather a tank designed to provide decades of un-compromised experience with proper care and feeding. So if you have every five years a sizable $6k to $8k maintenance bill, you still are net neutral driving your beast of a car that is as satisfying as the first time you stepped on the twin turbo while getting your back rubbed and sides bolstered. You either pay to maintain your car in top shape, or you pay to replace a lesser box of metal every 8 years and incur the wrath of depreciation.

Two competing philosophies (I hope). For now, I'm going to roll the dice with the MB.

That seems like a good and reasonable conclusion, especially if you gained some concession help for the repair.

Yup, I agree with you. I love my E550 and I plan on keeping it. It is worth it to repair rather than dump and get something else. Good luck

What a nightmare!
 

[QUOTE=holminone;7691680]


I'm living through this terrible issue right now with my 2012 E350. $11,000 worth of damage from the leak - even though I just had the 80,000 service that inspected for leaks.

I'm living through this terrible issue right now with my 2012 E350. $11,000 worth of damage from the leak - even though I just had the 80,000 service that inspected for leaks.

I would not put $11k worth of repair into a car worth maybe $15k max. Dump it for whatever price and move on. Maybe find a reasonable mechanic to fix the immediate problem first. That sounds like rediculous dealer pricing.