How can the mass airflow sensor even get dirty if I have always used genuine filters? - Mercedes-Benz Forum

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post #1 of 5 (permalink) Old 10-25-2011, 01:33 PM Thread Starter
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How can the mass airflow sensor even get dirty if I have always used genuine filters?

How can the mass airflow sensor even get dirty if I have always used genuine filters? (and replaced regularly every 6 months, regardless of mileage)

The service advisor said that even if my air filter and filter housing are in perfect or new condition, the MAF sensor may still get dirty. If so, what's the point of having an air filter in the first place?

I'm not really concerned about the dirty MAF... I went home and cleaned it out myself with a $6 bottle of MAF
cleaner... what I'm concerned is my engine not getting 100% clean air.

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post #2 of 5 (permalink) Old 10-25-2011, 11:10 PM
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Do you think if the filter only captures 99.9% of dirt, you could as well remove it and let the engine eat 100% of the dirt instead of 0.1%, because your MAF anyway gets dirty at some point?
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post #3 of 5 (permalink) Old 10-26-2011, 07:17 AM
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100% clean air . . . do you drive your car inside a microprocessor manufacturing plant?

First, how often does the MAF get fouled? It sounds from your post that this is the first time after several changes of air filters, which you do twice a year. That may indicate that it was possibly a fluke event, perhaps a drive through a particularly dusty or gritty area or season.

Second, the alternative of not running an air filter makes no sense at all.
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post #4 of 5 (permalink) Old 10-26-2011, 07:29 AM
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I have always run relatively clean air filters and my MAF started setting a CEL after 90,000 miles (code was P0170). I'm glad your cleaning regimen did the trick (you are one of the few exceptions), I just replaced mine.

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Last edited by Musikmann; 10-26-2011 at 07:35 AM.
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post #5 of 5 (permalink) Old 10-26-2011, 08:40 AM
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Per my observation the MAFs on gas engines just fail with no obvious problem. I have seen several of them that even with magnify glass look perfectly clean, yet the engine would not run with them. My diesel engine has 226k miles on it and the MAF is likely original. I do oil testing and it will show filtration leaks in higher silica. My shows perfect.
Also I installed filter gauge on my box. So far after 50+ thousand miles there is no indication I need a new filter.
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