Leaking oil sensor on M271 engine
 

I noticed quite some oil around the oil sensor and subsequently in the connector. Has anyone had that before? What causes it? Defective sensor or only the seal?

This has been discussed on the forum for many years and millions upon millions of time. Please use the search function!

Here's a thread that will get you started https://mbworld.org/forums/c-class-w...m-sensors.html

New O ring - common.

Thanks guys. I am currently replacing the cylinder head (misfire cylinder two, low compression), the cam sensors and the harness. I will now also replace the oil sensor o-ring to ensure I don't have another source of oil entering my harness.

Please put your car's year, your location and other information in your shared profile to help out...Thanks!

Hope you get all of this fixed...there is also (depending on your leak) a pigtail you can add on to protect and isolate any future leaks...

and here's a youtube video that explains the complete procedure. The narration is in Spanish, but it's really self explanatory - good enough to be made a 'sticky' in my opinion.
http://www.youtube.com/watch?v=PoeSSEmpsHM&translated=1

I put everything (except two M6 x20 bolts???) back together and the car is running again. Thanks for your tips.