I have posted this on the ML forum but I've not had much success. Since these OBD 2 codes are generic I thought I'd try here.

I'm getting codes P0170 and P0173. Vehicle a 1999 ML 320 with 133K miles runs fine and mileage is good.

Below are the explantions for the two codes I'm getting now. Nothing is mentioned about the MAS. I wonder what the problem is.

Attached Thumbnails

   

IF you lived in Vegas & were a gambler then the air mass sensor (112-094-00-48) would be a 98/1 bet!

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That's what was discussed on the ML forum too. If just seems odd that the workshop manual, i.e. what I got from Alldata DIY which I posted in the thumbnail did not say anything about the MAS.

I had the same codes in my 97 S500 and I changed the Air Mass Meter and that fixed the problem. Also, the engine seemed to have a little more snap after the change. As you probably know, these codes represent an exceedence has been recorded in the ECM's ability to "adapt" to a rich or lean condition. As I understand it, either a bad AMM on the intake side or O2 sensors on the exhaust side can lead to adaptation values to be exceeded. If you only had one cylinder bank throwing you a code, it could be either the AMM or an O2 sensor but since you have both banks throwing you the same code at the same time, chances are great that it's your AMM since it would be quite a coincidence that more than one O2 sensor would fail at the same time. This is as far as my rice paper thin knowledge goes regarding adaptation values. All I can say is that I replaced mine and all my problems went away!

If you want to know more about adapation values than your local MB tech, read this: http://benzworld.org/forums/forums/thread-view.asp?tid=1203330&start=1&fid=13 Look about halfway down the thread on the first page. The article is titled "Adapation Values" (I think it originaly comes from Stevebfl- so thanks Steve)

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Paul Hansen

1997 S500 (100,000mi)