I have a P0170 code happening again on my 1999 C-230. From searching, I see that the two common reasons for this code is the air mass sensor or the fuel pressure regualator.

I replaced the air mass sensor about 18 months ago (which instantly solved the last p0170 code problem), so I wonder, do they go bad that quickly? I drive lots of highway miles, so the new one probably has 50,000 miles on it. I also noticed that the large hose entering the air cleaner box has a black tar film in it. Anyhow, should I have the adaptation codes read or just replace the air mass sensor replaced again? Thanks for the help,

Don

PS - what do they charge to read the codes?

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2008 ML350
2007 Honda Element
2007 Honda Accord
2009 Honda Civic