selwyng

Hi Guys

So i have oil in my wiring harness. I called the dealership and they informed me that there are 2 types of harnesses on the w203, the Engine harness and the Body Mounted harness.

The price on the Engine Harness is R5648 ($728 USD) and $1238 USD for the Body Mounted harness.

Which one do i need to replace? Is it the Engine harness or body mounted harness?

Glyn M Ruck

The engine harness!

selwyng

Thanks Glyn!

Would you know if its a hectic job to remove and replace the harness?

SunnyRayToronto

At those prices, you should try cleaning the engine harness first. Use an electronic spray cleaner like CRC QD Electronic Cleaner,........... SEARCH for the DIY threads.

selwyng

Thanks SunnyRay!

I did try searching the forum.. didn't find anything. Maybe i'm incorrectly searching. Will try again.

amanonfire

The issue:
https://mbworld.org/forums/c-class-w...m-sensors.html

Unfortunately we don't know much about markets outside of North America, if there was a recall, if all VINs are on the TSB, ... so you are better off DIY fix for < $300.
https://mbworld.org/forums/c-class-w...nsor-leak.html

I would not replace the harness and spend your money replacing the O2 sensors instead. The harness will not contain a lot of oil, so as long as you stop the leak whatever oil is left will be minimal.

C230 Sport Coup

There was a guy 'Herr Kranz' or Krantz that pulled his out, soaked it, got all the oil out and put it back. He said it was about 8 hours total.
Search by user name.

Glyn M Ruck

Ichibans also removed & cleaned. Bit of a PIA but not too bad.

BTW - I think Benz should replace FOC. It's their f/up.

selwyng

Thanks amanonfire!

I don't think MB South Africa ever had a recall on this problem. The leak has been stopped and the pig tail wire fitted. Will need to find a decent mechanic to undertake this job.

selwyng

Thanks C230!

selwyng

Thanks Glyn! BTW whats FOC?

Glyn M Ruck

FOC = Free of charge!

EDIT - Did you find Ichibans thread?

derecklouthood

I just had this replaced along with TCU bushing, check this as oil as perhaps leaked or broken clip. It can have oil under passenger floor board. Where connections is made.

To have replaced engine harness, along with cleaning of TCU and ECU, with o2, cost around 1700 CAD.

Sucks, and the next week i had a metal shard in my tires, had to purchase new tires.

Get this fixed asap, as it can fk your car.

amanonfire

If you can turn a wrench you can DIY and see how it goes before replacing the harness. Since you've stopped the leak there will be very little oil left in the harness, so its not like your car will get must worse than it is today. If you clean all the connections and your gas mileage improves, then I'd live with it and save yourself $1700 that derecklouthood paid.

First, replace the cam actuators if they haven't been. $50 each, only 3 bolts each, right on the front of the engine so very easy to do.

Next, buy a spray can of electrical contact cleaner. Follow the cam actuator wires back and eventually you'll make it to the ECU. On the way you'll find places where the harness branches, follow those out to the connector. Unhook the connector, spray both ends liberally with contact cleaner, let dry then reconnect.

Almost all the connectors will be easy to find and undo without requiring any tools. The only hard ones are 3 under the car: the O2 sensors and oil level sensor. To clean these, jack the drivers side front up. Remove the furthest back undertray panel and you'll see the oil drain plug. All 3 connectors are right around there. Spray the hell out of these, several times. The sending units for the O2 sensors are in the connectors and probably full of oil.

Put everything back together and monitor your gas mileage. If it gets better you're done. If it doesn't, you'll need to replace both O2 sensors which there is a good DIY on this site to follow.

I tried to convince derecklouthood to tackle this himself, and you'll see that he paid $1700 as little as $200 to DIY. Even if you have to replace the O2 sensors, its still < $400 to DIY.

derecklouthood

I know i know But wire harness was filled with oil. just the 02 sensors are around 350. i def. needed a new harness, and even if not, preventive maintenance. I think the car had the 2 cps faulty since i purcharsed with 86k(currently hit 130k) so, im happy it really didnt have oil everywhere.


Just happy to have my car and hope no one has to go through this. Serious PITA. This site has saved me money and I will do some certain thing. However to replace a harness and potentially mess up anything else... Would of cost me more. But big thanks to amanonfire for the tips

amanonfire

No problem. Wish I could've helped more, yet I won't be back in Ottawa till July.

Did you try sourcing the O2 sensors in the US? I remember paying $80-120 each, as one was much cheaper than the other.

selwyng

Thanks Glyn! Nope i didn't find the thread specific to him. But i did find other threads that are similar

selwyng

Thanks amanonfire!!!! I will give this a try myself!! Would the wealth of knowledge on this forum and advice from the fellow members, i don't think i could go wrong

Glyn M Ruck

Here is one of his threads. He put the harness in alcohol.

https://mbworld.org/forums/c-class-w...light=Ichibans

Russell Ormerod

HI Selwyng,

Do you have running issues other than oil in your harness?
usually once the oil gets down to your O2 sensor plugs you may develop running issues.

Glyn M Ruck

+1^

amanonfire

No problem, let me know if you need any help.

You'll notice from the link Glynn posted that the alcohol bath doesn't have much oil in it after soaking the harness. That's cause small braided wire can only hold so much oil, and its a minuscule amount compared to what you'll flush out of the O2 sensor sending units. Thus why I don't believe its worthwhile to replace the harness, especially since only half the harness is affected. You'd be better off revisiting the cleaning a few times down the road as the last of the oil works its way out of the harness. This is why I'd recommend not replacing the O2 sensors at first. Clean everything and monitor gas mileage. If it doesn't improve then replace the O2 sensors and hope most of the oil has worked its way out the bottom.

Good luck, let us know how you make out.

C230 Sport Coup

Just curious why it isn't possible to clean the 02 sensors?

C230 Sport Coup

Damn I'm good! I never followed up on that thread.
I see I nailed it! Did he ever follow up with the solution to his trans problems?
Personally if I had this problem, I would probably want to pull the harness and get all the oil out.
If the oil is in the wiring, it can effect the electrical characteristics such resistance and capacitance and those are the things our cars look for.
Too much resistance going to a bulb? Turn it off.
That kind of thing.
I need to pull the mirror blinker and clean the contacts.
Mine is fine the computer doesn't think so, and keeps turning it off.
Probably just need to clean the contacts.

Point being, the oil in the harness does 2 things.
1. It messes up some of things it's connected to such as 02 sensors
and
2. It changes the electrical characteristics and causes incorrect values to be sent back to
car's many little computer brains. A major gremlin.

Wow, Ichiban pulled the SC? That takes a little while, and you'll want to order the new gaskets.

amanonfire

Some have reported cleaning works, others have reported they needed to replace the O2 sensors. The sending units (aka the electronics) of the O2 sensors are in the connector, and I'm guessing oil fouls them over time.