Hi, I have a 2014 A207 with 67K miles and the M276 engine.

I have been told by two separate indie shops that I have the dreaded oil in my ECM from the wiring harness.

The first one said they cleaned out the ECM and it appears to be fine, but both shops said that it will just keep happening unless I do the fix. The quotes for the permanent "fix" were $5300 and $4600, respectively, but the first told me just to move on from the car at this point unless I planned to keep it "for another decade." The second one said it might never cause an ECM failure, but that it probably would - the question is whether it would happen now rather than later.

The descriptions of the job were basically identical - to replace the wiring harness and a few sensors - cost is mostly labor and the difference in quotes is effectively the hourly labor rate (the first one has a few more hours quoted). If I wait until the ECM fails, add about $1500.

I think I tend to believe them since they both said it independently - I brought the car in to each shop for a totally different issue, and didn't mention anything about the other shop to the second shop. But this would literally be the most expensive car repair I have ever considered. I know there are a ton of threads about this issue on the site, but to be honest, in reading them I got a bit of information overload and really couldnt' figure out what the "fix" actually is. These are both "higher end" shops, though, so I wouldn't be surprised if they tended to "over fix" an issue. So is this really what I'm stuck with?

Thanks

 

So it's really in your court. You have to decide if you want to keep the car or move up to a newer model. Given the way used car prices have been, it may still be worthwhile to repair, but then again, it may not, as prices have leveled somewhat.

It's really your decision, but unless there's some deep sentimental reason to keep it, I'd say, just move on to a newer model. I'm still getting offers from local MB dealers to buy my MY2015, but I'm not a fan of the new models' design, both exterior and interior. If I get a 5k repair bill, I may reconsider...

 

I would love to see the quote. What parts and how much labor?

 

I have an M278 with the same issue. Oil hasn't reached my ECU yet, but some of the cam position sensors/actuator plugs were dripping wet >:|
Being a redenck n all, I'll be fixing it myself. No way I'm paying someone. So here's my thoughts on options:

Buy some sacrificial wire plugs to at least stop more oil getting in; Link Or buy new cam position sensors/actuators that don't leak. The newer ones aren't supposed to leak, so they say, but I bet it's still a gamble.

Open up the ECU and put some paper towels in there to absorb the oil, replace now and then. My guess is it isn't much oil at all but you'd know more than me. There's a spot, at least in my ECU, where you could stuff a wad of paper towels in there nicely so even when wet it won't touch the board. My ECU sits with the board on top and the "cover" pretty much looks like an oil sump, so as long as you can get the incoming oil to divert to the pan, I'd imagine I could hold a lot of oil. Not sure what your ECU looks like or how it's mounted, but where there's a will there's a way. Even if I had to seal the whole board with something, I'd do it.

Seal the ECU so oil can't get it. It can only seep in via the pins that pass through the plastic in the ECU and clearly they aren't sealed. What sealant to use, I don't know yet. I was thinking silicone or epoxy. How much room there there is inside the female plug for that I don't know, but if there's 1mm of space between the male and female plug then there's your limit, but I'd imagine there's more space than that. Since you already have oil in there it won't be so easy to get a good seal, plus it'll weep up n out the pins and may work its way under the sealant over time and break the seal? But maybe this would take years to do that so good enough?

If I were you I'd buy a replacement junkyard ECU and load your data onto it. That way you have a nice dry ECU to seal, and your data saved on a hard drive if you ever need it. Plus the old ECU, which you've now cleaned out, can now be a spare to keep in the trunk if you ever run into trouble. I bought a spare ECU from an online junkyard for $200, plus ~$80 in hardware to make the data Xfer. Totally worth it and I can explain how if you want to do that.

You could also drill a small hole in the sensors/actuators to let the oil out. Not sure how well this will work but imo it's better to let it drain out than have the plug completely filled with oil all the time. If you've ever pulled a plug on one you'll see the male plug has the seal and you don't really want to cut the seal to allow it to leak out because it would still need to fill up with oil to do that. A hole in the sensors/actuators would be at the very bottom, plus those sensors/actuators are consumable items, like spark plugs, your harness is not as you found out via the quote. I would also insert a wick into the hole to draw oil out and let it drip on the eng instead. Something like thin cotton string or strip of cotton fabric. I'd imagine that would both stop more oil from entering, but also pull oil out of the wires.

My plan, for my car, is to suck the oil out of the lines. Same drain hole in each plug, but I plan to run a tiny tube to each one and them to the vacuum pump. How well this will work I don't know, but it's a zillion times better than doing nothing.
Option two, which may be better: Pressurize the ECU. Force the oil back out and down the wires. This way it can run while the car is parked so you get much more time spent doing its job. Plus and you can use more pressure. How much will get past the ECU's pins I don't know, but probably not much so you may also want to pump air into the plug to push oil down the wires. If you don't have a hole in your leaky sensors/actuators then you'll want to unplug the ones that are leaking. The air you pump into the ECU needs to be dry and oil free, which isn't hard to do. You have to make a filter, store boughts don't work, but I can explain and it it's cheap. A small little compressor is like $100? Filter assy and hose maybe $50?
So while pressure is better, it's also more hassle and $. Since I don't think I have much oil I'll go the vacuum route, but fyi those are the options, imo.

 

The fix is indeed to replace the harness, cam position sensors and cam magnets. A new ECU may or may not be required, depending on the extent of oil infiltration into the ECU.

The minimum fix is to replace the cam position sensors and cam magnets. Then clean the ECU connector with CRC contact cleaner spray periodically. Residual oil in the harness will continue to work its way wherever it wants to go, and you can clean it again and again, as it presents itself.

If you DIY, the cost for the harness and electrical parts is not terrible. The time to replace the harness would be something to consider. If I was doing this, I would make it a weekend, or long weekend, project. Start Friday afternoon and button it up Sunday night or Monday night. The main cost driver for an indy or dealer to do this job is labor hours.

 

How many miles do you have on your 2012 E550? I just turned 80k kms... and am thinking of taking a look at this next time I'm in there. Just wondering if anyone has established a mileage lifespan on these parts. Thanks in advance.

 

No clear mileage threshhold when leaking starts. It doesn't seem to be an early failure. Roughly I would say around 50k miles is when problems start to surface, for cars that don't have the most recent part numbers installed.

 

Had another indie tell me he didn't think that after the sensors and magnets there would be a need to replace the harness, since there's no additional oil entering the harness to "push" the existing oil from the harness into the ECU. He says under $1500. So now I'm in a quandary. Plus, my Nav screen just died (about to post on that), so I'm thinking I may just sell the thing and buy a Toyota.

 

best i can do on my phone. Hope that’s legible.

 

Deduct approx $600 from that quote for resealing front cylinder head covers, which is unrelated to the complaint of oil in harness. Seems like they want to give you a hip replacement while you are in there for a heart catheterization.

 

Took it to indie 3 today. He showed me the harness connector, which has a fair bit of oil on it, but then none of the connectors show any evidence of oil penetration. He said the last two he looked at were like this - the leak was not at the camshaft sensors.

 

Where did he show you was the source of the leak?

 

He was noncommittal, and made me nervous. Indie # 4 also said he could not find a source, but replaced all 4 sensors and magnets. He also removed the harness and cleaned it, then hung it upside down for 2 days and there were no oil drips at all. Just to be sure he cleaned it again though before he reinstalled it. Said he thinks it’s good but we should check every 500 miles for a while. Cost under $1500.

 

P0342 (Camshaft Position Sensor "A" Circuit Low) came up and now I'm reading about this M278 issue of oil leak from camshaft sensors which seems to be quite common in the M278 engine... I suspect that is what is happening. Going to get it to the shop next week to check.
I have read cases where oil goes so far into the engine harness and people have to replace hardness, ECU, O2 sensor, etc. If the camshaft. If the error has just come up what's the likelihood that the oil has gone far into the harness?
My plan is to have the mechanic confirm the presence of oil, and if the oil hasn't traveled too far up, change all cam sensors (the newer version of the sensor supposedly has a revised design?) and also add pigtail extensions to isolate the engine harness...

 

In my previous post (#4) I did finally "suck" the oil out and it worked as expected. It didn't take long, less than an hour, before no more oil came out. I left the vac lines on it to continue sucking, because why not and now I don't have to change the sensors. Hard to gauge how much oil came out but I suppose 5-10 drops? I only had two leakers bad enough to bother with, which are in the pix below.

If it were me I'd do the vacuum mod and open the ECU for cleaning. I'd also put paper towels in the ECU, to collect any residual that finds it way and around again. I'd do the same with the ECU plug, to help suck out oil from the other wires that migrated into and from the female plug ends which will hold oil. The vacuum mod might pull oil from the other wires, but it'll just accumulate in the plug, which is what the paper towels are for. Probably not much in the other wires, but only way to find out. Oil will be hiding in the female side of each plug wire, so spray those out good, and do each time you're in there. If oil got into the ecu then I'd imagine it was forced in. If so, then I imagine same with the wires. I don't suppose you saw how much oil was in the plug? Whatever the case, oil was likely forced, or wicked, down some of the other wires. Just have to spray and paper towel it and see what happens, but I bet this is totally fixable. Sure you may need to check/clean once in a while, but that repair bill is much worse.
I know most people will just pay to have the harness replaced, but after seeing the price vary from 4-8K, I'd assume a few people would be open to my redneck fix.

Optionally, here's some easier versions, and they get easier as I go:
If the vacuum mod I did is too much, I'd simply use vacuum to suck the unplugged connectors. Just stuff the plug into a glass jar and mod the cap to accept the wire, or use a piece of plastic or whatever to make a cover for said jar. I'm picturing a Snapple bottle, easy size and the mouth is probably perfect. It's ok if it's not glass, but ideally is should able to handle the vacuum and not collapse. You can use silly putty, duct seal, wax or whatever to make a seal around the wire, maybe elect tape tape? Then, also in the cap/cover, or bottle somewhere, you'd have a tube to connect to vacuum from an engine. A vacuum cleaner doesn't actually make very much vacuum so it would take substantially longer and do a crappy job in comparo, but if it's all you have, it's a zillion times better than nothing.
Then with the ECU unplugged, and sucking in progress, I'd spray carb cleaner into the plug. You should be able to tell which wires you're sucking on as they should suck carb cleaner in? You can watch your progress in the jar, which I imagine will be slow, but even 10min will probably get most of the oil out if it. Do that to each of the offending wires/plugs, or make bottles for each and do it all once. I'd check/clean the ECU plug now and then as residual oil will no doubt bleed all over again, depending how much got where.

If that's too much work then I'd just douche the ecu plug with carb cleaner, wipe/pat with paper towels and let it dry for a bit. Then put paper towels in the plug to absorb as you drive, check/replace paper after a drive, repeat as needed. My guess is you will only need to do that a few times the first week, then maybe once in a long while? Assuming you replaced leaky sensors, obviously. It'll always have oil soaked wires, and that may bleed out for years, but as long as trons aren't going where they shouldn't, it's good to go.

If that's too hard, just douche the ecu plug with carb cleaner maybe once a day for a couple days, ideally just after driving it. Then when you see less oil coming out I'd do it maybe once a week for a few weeks. Each time you spray it out, use a paper towel to catch the mess, to see how much oil comes out. Then use paper to soak up what you can from the female pins, and let it dry out for a bit. Only doing it will tell how effective it is. Maybe after several times will be good enough, maybe once a day for a month, but we won't know until you try.

If you do any of these, let us know how it works. I'm sure a success story will encourage others to save $4-8k too.