Question about 2001 Mercedes-Benz E-Class

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Check Engine light came on (2001 E320 with just 20,000 miles on it). After connecting the scanner, the code showed P0 170 and P0 173 which I was told was a Mass Air Flow (MAF) sensor problem. I checked the MAF sensor and it looked very clean and like a new part. 1) Could it be very likely defective MAF part even with a low mileage? 2) Can a MAF part be tested/checked externally? 3) If MAF is OK, than what other part could the code numbers be pointing at? Thank you for your help in advance

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Good explanation regarding air sensor,for my opinion,visual check for unmetered air(air leak0,maybe fuel octane reseting.

Posted on Feb 01, 2009


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Those codes do appear to deal with the mass airflow sensor. The MAF sensor is probably the "hot wire" type where a thin wire is suspended inside the body of the sensor and is heated with electrical current. The amount of air passing over the wire is directly proportional to the resistance of the wire and that resistance data is calculated. The MAF sensor, by itself, cannot determine the air mass supplied to the intake plenum. One or more other sensors are used in conjunction to equate these values. The oxygen sensor(s), Manifold Absolute Pressure (MAP) sensor, the Intake Air Temperature (IAT) sensors may all play a part in this fault reading.

There are reliable methods to test the MAF sensor. One well takled about method is to tap the MAF sharply with a screwdriver handle while the engine is running. If the engine dies, the MAF is faulty. This can detect a physical defect in the wire and a few other things but do do assume that, after repeated blows to the MAF with your dead blow hammer for good measure, that the MAF is at 100%. I will research some text on testing these sensors on that particular model and post links to any information and diagnostic data I find.

Posted on Jun 04, 2008


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