Hi all, I'm new here hopefully posting correctly.
I have a 2012 ML350 Bluetec, first was a bad fuel leak at the filter, replaced filter all seemed fine then the CEL came on about a week later with P0101 code of course couldn't be more Generic.
I figured it had to be something I did so went back over everything. Did find the Green O-ring at the Turbo inlet worn/weak replaced it along with air filters did best I could to check all hoses, tubes, vacuum lines etc.
I do not hear any hissing or sounds to make me think a leak in the system.
What I do see is a oily Engine Breather PVC at the inlet to the Turbo with some oil coming from it.
It could have failed causing a vacuum leak so I have one on order but does anyone know a way to bench test this valve? We do not have many dealers close for a quick pick up.
Is it powered or resistance can it be checked to make sure it's bad?
I also purchased the iCarsoft MBII for Mercedes Benz/Sprinter/Smart Professional Diagnostic Tool Scanner, New Version,
I am getting Pending and Permanent P0101 but no confirmed. I know I will not be able to clear the permanent code but I also don't seem to be able to clear the pending. I can turn off the light but comes on soon as I start back up unless I leave the reader connected during start up.
Thank you so much for any help!

 

Also the reader I purchased has real time so I've watched as we drive the MAF sensors seem to be functioning fine.

 

With a generic OBD2 reader, I doubt if it's ever going to give you useful information. You need a Star/Xentry system to give you REAL trouble code and instructions. Find someone near you who has it or you can buy a cloned one from aliexpress. I bought a Xentry set for about $450 with a SSD and then I put the SSD into an old X61 laptop it works like a charm.

The OM642 has 2 MAF sensors. They can be cleaned and then you will need to use the Star/Xentry to calibrate them. No aftermarket OBD2 reader can do this work.