Cleaning the harness means using CRC spray on the connectors.

Have you opened the ECU connectors and checked for oil on the pins? This connector is subject to oil penetration and also needs to be cleaned if oil has reached it.

 

Missfire in 1 not necessary related to oil in harness. Could be many reasons, not only oil. Clean coil socket as well, it gave missfire on mine engine.

 

Cleaning sockets of oil is helping system to function. You cant really remove oil from harness itself, however if wires insulation intact you don't really care. Replacing ECU is a last stop in the journey, only after all measures are taken. Just carefully splay with electronic contact cleaner and let it dry. I would keep ECU connector on downside to make sure no spray will penetrate ECU due to gravity.

 

Thanks for the replies.
@arsupisemnet
ignition coils were swapped between cylinder 1 and 3, misfire remained in cylinder 1 so I believe the ignition coils are functioning properly

Things I have done so far:
removed ECU and cleaned all the oil from the metal pins. sprayed tons of CRC on it, turned it upside down however no oil came out of it, I suspect it is waterproof so no oil can actually penetrate it, still waiting for confirmation from someone on this...
cleaned the big harness connector attached to the ECU
replaced all four camshaft position sensors and cleaned their connectors, 3 of them were leaking oil
replaced two of the four camshaft solenoids/magnets that were leaking around the edges, their connectors were dry, no oil found inside
checked the fuel injector connector on cylinder 1 for oil, none found
checked the ignition coil connector for cylinder 1 for oil contamination, none found

I haven't check the O2 sensor connectors however contamination there should not cause misfire in only one cylinder, I believe.

Dealer has checked the voltage at the ignition coil of cylinder 1, here is the mechanic's note (translated form Japanese):
"Inspection with HMS99 Waveform inspection Primary waveform \ Normal. Secondary waveform Peak voltage is low (20KV)."

He didn't do compression or leakdown test on cylinder 1, neither a visual inspection of the cylinder walls with a borescope.
He also didn't check the fuel injector of cylinder 1 so it still could be an injector malfunction that coincides with oil in harness.

However the low voltage let's me suspect that it is an electrical fault somewhere and chasing it down could be really difficult and time consuming.

Estimated cost for wiring harness replacement $1,700 including parts and labor + tax.

Can the dealer check the whether the ECU is functioning properly without actually replacing it?
Just throwing parts at it is not what I prefer to, however that seems to be the dealer's preferred way.

I don't know any indy, the one I found refused to work on it because I am not Japanese.
Literally, he told my wife "foreigners are troublesome" and gave a dumb excuse why he can't check the car.

 

Bring it to MB dealership and do dynamic compression testing to sort compression issues. If no compression issues - change fuel injector. Secondary weak low means wrong fuel/air ratio. https://www.underhoodservice.com/dia...tion-problems/

 

If swapping coils didn't solve it, try swapping injectors. It does seem fuel injector-related.

The cost to replace the harness is a bargain. Another poster recently reported he was quoted almost $8k.

XENTRY scan will bring up codes in the ECU. If there are no current or stored codes, the ECU is functioning properly as far as the car is concerned. Intermittent loss of electrical contact anywhere in the system due to oil in a connector may or may not store a code.

 

An update.
The problem has been solved by replacing the fuel injector in cylinder 1, compression check was OK.
So the oil in the harness and a LOT of oil in the ECU connector had no effect on the running of the engine.
I cleaned the ECU connector, I replaced all four camshaft position sensors, as I mentioned earlier three of them were leaking oil into the harness, and I also replaced two of the camshaft solenoids as they were leaking at the gasket but not at the connector. I guess I could have just replaced the O-ring as their connectors were dry. I may save them for later...

I will check the connector of the Bank 1 upstream O2 sensor, as it has thrown codes a few times, for oil but other than that it seems to work fine.
So I am not sure if oil in the harness actually causes a lot of problems.
In my case it has caused, so far, none.

On a side note, if oil in the harness would cause so many problems then logic dictates MB Japan would have harness in stock.
They've got none in Japan, not for the M276 engine at least.
I asked the parts department to give a price for the ECU and the harness.
They said there is no harness in Japan, I would need to wait about two weeks to get one from Germany.
So perhaps a total replacement of the harness and the ECU is, a very expensive, overkill.

As I mentioned earlier, I tried to get the oil "out" of the ECU, should some have leaked into it, but none came out, the ECU is a sealed unit.
And since oil is an insulator I don't see how oil in the connector could cause an ECU issue.
I understand there are additives in engine oil however the pins on the ECU and the connector contacts are a really snug fit so I don't see how oil could get in between them and perhaps increase resistance or cause no contact issues.
Can anyone explain that, thanks.

 

Coming back with an update after two months. To sumarise, I got oil in my engine harness and the oil reached the ECU, 3 injectors, 2 coil packs, O2 sensors, camshaft and crankshaft sensors.

Up until last week, the independent Mercedes shop I took my car to had multiple back and forth interactions with my 3rd warranty company. The shop was awesome in dealing with the warranty company. The owners even prepared a presentation for the warranty company.

The warranty company is paying a significant amount of money to get everything done right. So I decided to go ahead and get the engine out of the car to replace the engine harness and a few other things.

Below is the list of things I’m getting replaced:
-Engine harness
-ECU
-All injectors
-All coil packs
-All the sensors the engine harness touches (camshaft, crankshaft, O2 sensors, MAF, etc.)(excluding the knock sensors)
(oil only got to the camshaft, crankshaft and upstream O2 sensors, but I want to replace all sensors since the engine is out.)
-Camshaft solenoids
-Almost every plastic and rubber hose
-Maybe a few more things

The shop got the engine out this week and they are working on getting everything replaced. Once everything is all set and done, I’ll follow up with another update.

Thank you everyone in this thread for the information and support. Here is a picture with my car with the engine out.

 

Pretty impressive car collection they're having there, in particular the 600!
Wonder what their total invoice will look like with this kind of work performed....

 

At what mileage is the oil in harness being found? My GL550 just passed the 60k and I checked all the cam sensor and magnet connections while I changed the oil. Found oil in 3x cam sensor plugs so I replaced all 4 from FCP Euro. If it happens again I'll send them back on their lifetime guarantee. I added some dielectric grease between the connections for good measure. I didn't see any oil on the wires past the plugs.

The magnets I think 1 had a tiny bit. Probably replace those on the next oil change for safety.

​​​I have an oil leak around the left rear of the engine, I'm taking it to a shop for transmission service and spark plugs soon, I'll have them investigate the leak. Hopefully it's not a huge job.

 

Nice! Sounds like you might be doing this, but don't forget about doing the engine mounts while you're in there. Also, perfect timing to replace the Turbos to upgraded ones =)

 

I wish I could have been made aware of this thread after I bought my 1st MB March 2020 - 2013 E550 4M 69k then - now 88k - took my car in to get Camshaft Positions sensors replaced(4) found oil - Camshaft magnets replaced(4) no oil - dealer said they found oil in wiring harness and in ECU - replacing wiring harness and ECU = 8k
ECU back ordered - No ETA

 

If the harness has been replaced, can you clean the ECU connector pins with CRC spray as a temporary measure until the new ECU arrives?

 

Update: M278 - oil in wiring harness & ECU - Warranty company said this repair was not covered??? - Dealer called them and that's what the dealer told me - so, I called - needles to say I got the same response (bummer) - did I buy a bogus warranty? - I had to bite the bullet & authorized them to replace the ECU (ME) and wiring harness - hope there's a remedy down the road where I can recoup my out-of-pocket expenses - will keep an eye on this and other related threads for future updates - (fyi) after repairs were completed took a trip to La (Lafayette - Abbeville) - no problems with the merc - I like my E550 4M TT's

 

Who's the warranty through? Lots of bogus ones out there.

 

Was the car malfunctioning?

 

No, I regularly come here to get the latest updates for my merc - I asked the dealer to replace my camshaft solenoids and my camshaft position sensors - that's when they told me about the ECU and oil in my wiring harness - not a DIY'er

 

If you're an attorney maybe you can help

 

I'm not an attorney but I did stay at a Holiday Inn one time. It doesn't say what coverage you have, at least, I didn't see it. If you have the platinum coverage, I don't see why it wouldn't be covered. Call, if you are in Texas: Unresolved complaints or questions concerning the regulation of service contracts may be directed to the Texas Department of Licensing and Regulation at P.O. Box 12157, Austin, TX 78711, 1-800-803-9202.

 

Well obviously a warranty isn't going to repair something that isn't broken. It's not a preventative maintenance plan. I just preventatively changed all 4 cam sensors in my GL550 at 60k miles. Found a little oil in each connector. Cost me $200 and 10 minutes for a little piece of mind, I didn't spend $4000 on a rip off warranty.

 

Welp! This thread has been far more valuable and active than I ever could have imagined more than two years ago. However, it looks like I might be back in the same spot... https://mbworld.org/forums/gl-class-...-stranded.html

 

New owner of 2014 wagon, I appreciate all of the information posted so far. I have ordered all new CP sensors and solenoid's. I should be able to replace all of them pretty easily except for the one next to the oil filter. I didn't see this video posted unless I missed it.

 

Good vid, I like his workmanship. Because the video was posted after nearly every post on this thread so far, it would not have crossed many owners' radars. Thanks for adding it!

 

I'm not mechanically inclined however, after reading this entire long post, I was able to successfully inspect and replace all of my 4 position cam sensors and 4 magnets.

My SUV did not have any engine codes or miss fires, I decided to verify and notice all my 8 sensor were all soaked in oil heavily and I was concern that it may have going into the ECU. I decided to take on this project for preventative maintenance. I rather spend a few hundred bucks on doing this than a few thousand dollars and dealing with a bigger issue.

Videos I followed:
(I did not remove turbo pipe)
(2nd opinion)
(ECU removal - inspected ECU wires)
(ECU removal - 2nd opinion)

Tools: You're going to be frustrated without these tools
CRC Electronic cleaner (use to clean ECU wires that connect to sensor and magnet solenoids)
T30 torx bit (Removal\add cam position sensor)
8mm gear wrench (Removal\add magnet solenoid)
Zip tie cutters (use to cut zip tie that holds the ECU wire going on driver side magnet solenoid)
mini zip ties (use to zip tie back the ECU wires back near driver side magnet solenoid)
74mm 14 flute oil cap wrench (removal of oil filter)
Torque wrench (add back the oil filter cap to 25nm spec = 18.4lbs)

Parts: I highly recommend FCP Euro, they offer lifetime warranty on these parts. If they leak again, you can swap them out.
4x Cam position sensor: https://www.fcpeuro.com/products/mer...-2769051000kt1
4x Magnet Solenoid: https://www.fcpeuro.com/products/mer...t-2761560790kt

I wanted to document the process but I was in a time crunch to get the family SUV back on the road. The job is very easy with the right tools and looking at the videos. Overal, I was happy that I was able to tackle this job myself and not have to spend a few thousand bucks in taking it to the dealer or indy.

I hope this post helps everyone to tackle this job. If I can do it, so can you!!!

(I can finally add this patch to my shirt)

 

My 2012 E63 wagon (70Kmi) just experienced the same issue and the local dealer quoted Me $10,500 to replace the wiring harness (25 hrs of shop time) and replace cam sensors. I asked if they could give me a quote just to replace the O2 sensor, cam sens54