I appreciate your help on the issue.
Currently the CEL is off again so if I were to replace the MAS while the light is out or off, will I fry or damage the new MAS?

I do have a local Auto Zone so if it comes back on I could have the codes read.

Also just filled up with med range gasoline.

Thanks again

I'm a little baffled by the on-and-off nature of your CEL (of course, I am mechanically inept); but I would at least try to clean out the air filter housing, maybe even clean the MAS again (I might try that jewelry cleaner technique with my old MAS, which I didn't have the heart to throw away). another great post re: this issue was by stevebfl, who posted a link to a superb article--technical but informative. search.

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2002 C230 Coupe + 2003 C320 4Matic Sport
http://img.photobucket.com/albums/v1.../sigpic5-2.jpg

Interesting, the one thing I forgot to mentioned is this whole situation happened shortly after the 50,000 service performed by the dealer. Maybe some dirt did get jogged around in the air intake.

Well I'll let you know how it goes over a week or so.

Right now I'm going to let the high octane gas get into the system and keep my hands off !

Regards

Just a quick contribution to this CEL thread. It seems that my 99 320 has had this malfunction light on for about 75% of the time since it was a year old. Four different shops have read then cleared the codes but the light always came back on within a week. At different times I've been told that the MAS or the purge valve may have been at fault. Codes reported to me include: PO300, 301, 130, 135, 170, 173, 302, 303, 442.

The purge valve was replaced about two years ago but the CEL was not out for long. Last summer when the MAS signal was again reported out of range, it ws changed. Following replacement of the MAS, the light stayed out -- for about a hundred miles.

In all this time, the vehicle has only stumbled once (while trying to pass a truck about two years ago). Otherwise, the engine has responded well and still sounds as smooth as the day of purchase. Gas mileage seems reasonable (but I should formally check it). Although I was originally concerned about the CEL being on, I've just learned to live with it. The shops involved haven't conveyed any urgency so no sense in loosing sleep.

Thank you for sharing your experience on the CEL.
Well I'm going to replace the MAS sensor. Found one new for under $200.00 so I'll see what happens. Maybe I'll get the black tape out and cover the light up if that does not fix it. ML is running OK so far.

For future reference, I'd love the know the source of the new MAS for under $200.....

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2002 C230 Coupe + 2003 C320 4Matic Sport
http://img.photobucket.com/albums/v1.../sigpic5-2.jpg

Drop me an email at smithins@bright.net and I'll give you the source for the MAS and other parts.