c3incjjc

I was told that oil was leaking through my cam shaft position sensor and into the wiring harness. Told we would have to replace 4 sensors and possibly the wiring harness if we didn't fix immediately. They said that oil leaking into the wire harness might cause a short and if that happens we would have to replace the entire harness. IT THIS TRUE? IS IT POSSIBLE? Can the oil really get into the wiring harness?

Thanks appreciate all input

BlownV8

Posting on the correct forum, X166, may yield better answers.

Miguk_Saram

If you are leaking oil from the camshaft position sensors, it is likely just a bad gasket. If your Check Engine Light (CEL) is not on, then you can simply replace the gaskets on the sensors. It is a simple DIY job, and would take about 10 minutes per sensor, if not less.


As for leaking IN to the wiring harness (as opposed to ON to the harness).. I don't know. Oil is corrosive to rubber, so rubber hoses and belts can potentially be affected in the long run - becoming brittle and cracking over time; the same would apply to wiring harnesses - cracking and possibly causing a short circuit (not a common occurrence).

Max Blast

Short answer, yes - if there’s a break in an electrical line that is submerged in oil, it’s done for. It’ll never conduct electricity properly ever again.

jerellorenzo

2012 cls550 83k
Sputter, engine light, P03410 - intake cam sensor error cyl 1 + P03420 - cam sensor short w218 cls550
replaced the driver side sensor closest to center ( not sure which one that actually is - haven't quite figured out the Xentry + WIS/ASCA )
The sensor side was covered with metal dust and oil and the connector was full of oil.
Replaced the connector ( broke the clip taking it off - anyone know how to f to not break these youtube is worthless 2022 on )
Drove about 3 weeks no issues
Sputter, engine light, P03410 again only
disconnected the connector - FULL of oil again - so to your question, no idea, brand new sensor was full of oil - my only assumption is that i did not clean it out well enough and as it is oil it heated up and distributed evently inside the connector. So I have it disconnected and gave it a good clean with some isopropyl, i'll hit it with contact cleaner too. May even take another go cleaning it.
I've not got the other one off as i don't want to break another clip.
The magnet is leaking oil underneath that sensor, so i'm going to swap that out as if nothing else the 17 dollar O ring needs replaced and i'm just swapping the magnet out too ( unless i can figure out WIS and or find out the voltage to test on a meter - ya know like a real mechanic )
so there's some info for ya. I can not imagine that this brand new dealer part leaked that fast. And the short code went away, so my guess is oil is my problem and i need to clean out the connector better - open to suggestions there - soak it upsidedown with contact cleaner maybe? idk
I see the last update was 2010. i think this forum is dead in large. but vehcile is 2012 so i imagine the advice would be the same.
that's my expirience.

chassis

From your description it sounds like the wiring harness is saturated with oil. Replacing sensors and magnets will not solve the recurrent problem with oil, if the harness is saturated. The oil will continue wicking out of the harness into anywhere oil has not yet migrated. If this is the situation with your car, the only solution is harness replacement, and at the same time replacement of all sensors and magnets. This is DIY-able but the harness replacement is quite a job. It has been stated on this site that the V8 engine harness cannot be replaced without engine removal. I can't confirm or deny this, but the claim has been made.

jerellorenzo

Thank you @chassis speedy reply, i had to go buy some e-torx... I will investigate how far any oil may have traveled up through the wires. The leak out the magnet is the at bottom, and that sensor wire is clean on that same side. I'll test the sensors with a meter. I would never think that oil would wick all the way to the ecm, but assuming the ecm is somewhere below the engine there you go. I suppose hating on Tesla for using a diaper wasn't so deserved after all, judge not i suppose. Just start weaving cotton thread in intervals as a notification system? This is the closest thing i have to a new blushing bride so the instant this happened it was investigated. Along the same lines i've read that once the leak is stopped oil will often wick back into the sensor as well. So oil is pretty much the concern with these in large in all directions. Thank you for the input. Time will tell. I certainly can not afford a new wiring harness in any capacity. But hey while i got ya, and not to daisy chain, but i'm curious if the plastic cover on the engine with teh little piece of insulation in there is necessary - don't need the heat in the summer, but do enjoy the paint on the hood...

And for anyone that can't get those lovely clips off here it is. ONE brave soul on the face of the earth posted an extensive how to:
"How To Remove Mercedes Sensor Connector"
https://mbworld.org/forums/e-class-w...ustration.html

chassis

Oil moves through the wires via capillary action, gravity is not a factor. Therefore ECU height relative to the magnets and sensors has no bearing on oil migration.

byroncheung

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...

eric_in_sd

@byroncheung wrong forum

jerellorenzo

Xentry will tell you which one. Thyre likely all leaking and need replaced. Wet connector means its bad

byroncheung

thanks @jerellorenzo . I don't have Xentry so I'm going to take it to a shop. I plan to have all of them replaced anyway to get some peace of mind.
I'm more curious about how far the oil would have traveled once the error code had come up. I hope I catch this fast enough so I don't have to replace the harness.

jerellorenzo

the Xentry is $1500 top end on ebay DOIP ( hacked ) so long as the update is after your car you're good. Those sensors are $60 each at the dealer, although they are bosch parts. There are 4. The dealer will let your ECU die long before they inform anyone about the issue. The clips will break, there's ONE post on here about how those work. Clean them first and use your fingers. it's kinda in and down and out a little bit, then just down and out. The connector still secures without the extra piece. New connector is $15 if you're particular. $160/hour at the shop. So my larger point is it's more affordable to get the Xentry as after one or two visits you've already got your investment back. You asked "how" this happens. It's either the physics of capilary or wicking. I think it's the first. The sensors start to leak, which is how the oil gets from the engine into the harness. There are 4 of them 2 on each side, so that's 4 entry points to the harness seemingly at the far end. The ECU is under the passenger seat, so gravity alone will track that path. You only need a new harness if the harness shorted out and that's like 25,000 on labor not to mention the car will be trash, everything will be lose and rattle. Anyway I questioned the same thing, it's not cotton, how's this possible. Answer is oil is being pumped onto the wires and it has to go somewhere, so it just flows slowly along the wire / insulation all the way to the ECU. Oil is petrolium, petrolium is corrrosvie to rubber, wire insulation is rubber, certain materials on teh boards as well - and that's how a stupid little sensor can destroy your Mercedes. The 4 magnets all leak out hte o-ring as well. Easy repair, use an open end wrench if you can't get the torx on.

eric_in_sd

Are you aware you are giving instructions for an entirely different motor than is the subject of this forum? Dude is on a x166, and you are presumably giving instructions for a x164 M273.

jerellorenzo

Yes I am. But it's a global problem, and this forum is not overly helpful to newbs. You are correct and it would be more advantageous to post in the proper build and specific engine.
And that is the latter part of the VIN - which NO ONE would tell me even though I posted that specific question. And half the people on here don't know what they're talking about.
To your point if there was a sticky with all the common problems no one would be making these posts because it'd be easy to find.
Like these stupid connector clips - there's literally one place on the entire internet that talks about it - it's on this forum - and it's still impossible to find and i've commented on it!
I'm holding this horses mouth in the water... i get it.

Thenumber7

i currently have the same problem. I’m curious. Did you get your car fixed? And how much did it cost you?

jerellorenzo

This is a real thing. The sensors are about $60 each. The 4 cam sensors are the ones that leak into the harness and drip down across that shield above the exhaust manifolds. The 4 magnet sensors leak oil out the front. It's easy if you don't loose any bolts.
Be mindful not to knock anything into your turbo intakes. An open end wrench will allow you to get the torqs behind the turbo tubes without taking the whole thing apart.

Sallad

Not true. Oil is an insulator. Transformers on power lines are full of oil for cooling. I build elevators and our hydraulic pump units have the electric motors and pump submerged in about 80 gallons of oil. (It runs 3 phase power at 600 volts)

jerellorenzo

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Go back to reddit. Motor oil in your ecu corrodes everything causing shorts which can destroy everything.

Sallad

Um ya, buddy, I'm 51, I've never been on reddit. I just know stuff.

...and its the heat that destroys stuff.