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If you're car is running well and you have no issues, it is time to install pigtail extensions onto your cam sensors and cam phasers.
I have a 2015 S550 with 72k miles on it. I have read extensively on the infamous "oil in my wire harness" issue that plagues the M278 engine (the Benz "550" engine in most late-model vehicles). For those who don't know, the problem is caused by oil that leaks from the cam phasers and cam sensors into the main engine wire harness. This oil travels along the sheathing and damages many downstream sensors and ultimately the ECU. Many M278 owners have had to replace the entire engine wiring harness as a result of this issue, which is about a $11,000 repair at an MB dealership.
MB has updated the cam phaser part numbers, but unfortunately the new parts still leak (as documented by my indy). One knowledgeable poster on this forum noted that "it is usually the cam sensors that leak, but everyone seem pre-occupied with the phasers".
I decided stay one step ahead of any issues are replace both the cam phasers and cam sensors on my car, which was running beautifully. This runs about $450 for genuine MB parts. And can you guess what I found? Oil had leaked past every one of my cam sensors and cam phasers. The wiring harness to the cam sensors was oily to touch, while the phasers were not yet. Hoping I can still avoid a huge problem, I did replace all of the parts. My ECU appears unaffected (some posters had visual oil on their ECU connections).
It is a small, sacrificial pigtail (extender) that can can be installed onto your cam phasers and cam sensors. It serves as medium so that oil does not continue spreading along the main engine harness.
MB does make a part for the cam phasers that comes off an older MB engine, but they do NOT make the part for the cam sensors which in my experience are much more prone to leaking. What I have posted above is the only solution. Fortunately I am your guinea pig, as I am now using them in my car and they are very good quality. In fact, quality is as good as the genuine MB pigtails for the cam phasers which I am using.
TLDR: Do yourself a favor, buy the above kit and spend 30 min installing it to avoid a very costly repair.
As someone who's looking into a M278, this will definitely be the first thing I look at.
My question is, what exactly stops oil from leaking into the pigtails and further traveling to the ecu?
The harness has a single piece sheath all the way to the ECU. These pigtails introduce a new sheath with gaps, and new connectors. So the right way to look at it is - when the pigtails start getting oily, get new ones (and new cam phasers/sensors).
Could you not just cut the sheath off somewhere close to the plug and angle the wires up so the oil drips out rather than creeping farther up the harness?
cfmistry, I already have the magnet pigtails from MB. Are you sure the position sensor (3 wire connectors) are correct for the M278? They plug in just fine?
S-Prihadi pointed out an issue with the 2 wire (magnet) connectors.
Camshaft Position Sensor wire kit - 3 pins
MB uses Hirschmann connector, FCP Euro one if from MB, means it is a Hirschmann.
Ebay one is a Hirschmann clone, you can tell by the grey/white lock. How good or not-so good, buy and tell.
cfmistry, I already have the magnet pigtails from MB. Are you sure the position sensor (3 wire connectors) are correct for the M278? They plug in just fine?
S-Prihadi pointed out an issue with the 2 wire (magnet) connectors.
This I am 100% sure of. I am using the OE MB pigtails for the cam phasers (like you have), and the ZZPerformance pigtails for the cam sensors. There is no other option for the cam sensors. They are on my M278 and working perfectly.
To show how much I like everyone here, I just went into the garage installed the ZZPerformance cam phaser harnesses and took pictures for you guys. Everything connects great, works great. Still recommend these 100%. $100 can save you $5000, which seems inevitable.
So, the difference between ZZ wire kit device side male connector Vs MB-Kostal is the outer lip "hugging" depth. The pin engagement section is similar, otherwise it wont fit.
Kostal covered its engagement section, while ZZ like Hirschmann keep it exposed.
This is what I meant by the engagement section. I dont know what else to call it.
Kostal seems to prefer design with longer outer lip "hugging" depth. Another example is my COP coil connector.
I don't mind buying ZZ phasor/magnet wire kit for troubleshooting purpose, as I can't yet find the FEMALE one.
BTW, i asked the eBay seller (ZZPerformance) if they could separate and sell just the sensor harnesses since I already have MB pigtails for the magnets.
BTW, i asked the eBay seller (ZZPerformance) if they could separate and sell just the sensor harnesses since I already have MB pigtails for the magnets.
So, the difference between ZZ wire kit device side male connector Vs MB-Kostal is the outer lip "hugging" depth. The pin engagement section is similar, otherwise it wont fit.
Kostal covered its engagement section, while ZZ like Hirschmann keep it exposed.
This is what I meant by the engagement section. I dont know what else to call it.
Kostal seems to prefer design with longer outer lip "hugging" depth. Another example is my COP coil connector.
I don't mind buying ZZ phasor/magnet wire kit for troubleshooting purpose, as I can't yet find the FEMALE one.
You are 100% correct, but the long story made short is... they work just fine!
After reading this thread I took a few minutes to have a look outside just to check on everything. Looks good on my end I snapped a couple photos to oshare if it helps anyone else in comparison.
Glad you took a peak, but you really need to disconnect the plugs and look inside both with a flashlight. That is how you will notice the "shiny oil" in the harness.
What my mechanic said.
Yes but we have found it’s not coming from cam magnets like he said. At the dealer, among all of us technicians, we have found that the oil is feeding into the harness from the cam sensors, which is a different part than what he is showing. We have also only found it to be really bad on the 276 engine and the 278 engine. I believe your white S class has the 278 engine in it. Your other cars are not affected by this. What I suggest is at around 80,000 miles we replace the cam sensors.
As a follow up for @MayorMcCheese he took his cam position sensors apart and noticed there was oil on both sides. So again, if you own one of these motors please do yourself a favor and get these harnesses before it's too late! I have nothing to gain from helping you all.
Yup - I had already bought the harnesses but wanted to check the sensor themself 1. I have the older sensors without the green gasket and 2. See the oil which did have.
I watched this video last night - it’s actually
a really good explanation.
I also only have 53,000 miles and the previous owner babied my W222
Yup - I had already bought the harnesses but wanted to check the sensor themself 1. I have the older sensors without the green gasket and 2. See the oil which did have.
I watched this video last night - it’s actually
a really good explanation.
I also only have 53,000 miles and the previous owner babied my W222
BTW, i asked the eBay seller (ZZPerformance) if they could separate and sell just the sensor harnesses since I already have MB pigtails for the magnets.
Does anyone know the origin of these pigtails? The reason I am asking is that there is a listing for identical looking 3pin harnesses for quit a bit (relatively speaking) less...shipping is from HK/China. If both are Asian produced (I would think yes), then it would make sense to buy here: https://www.ebay.com/itm/374594664256
02-08-2023, 06:39 PM
