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On average, the cost for a Mercedes-Benz S420 Mass Airflow Sensor Replacement is $440 with $345 for parts and $95 for labor. Prices may vary depending on your location.
The mass airflow sensor is a round tunnel made of plastic with a sensor attached inside. All cars take air from the outside and pass it into the engine through the air filter. The mass airflow sensor measures the amount of air entering the engine. For an engine to perform properly, it needs a specific amount of air-fuel mixture. The computer in the car reads the amount of air coming into the engine from the mass airflow sensor and then calculates the correct amount of fuel needed for proper engine performance. If the sensor goes bad, the engine will not know the right amount of fuel to add, causing problems including poor gas mileage, lack of power and more.
It is common for the mass airflow sensor to get dirty (if the air filter is dirty) and lose the ability to read the amount of air coming in the engine. If the vacuum hoses are leaking, it will give the same error code as mass airflow sensor failure.
When doing this job, the mechanic may recommend changing the electrical connector that connects the mass airflow sensor to the car's computer system. It is possible for the wires in the connector to break, causing the mass airflow sensor to not work.
In order to run optimally, your vehicle needs to have a perfect fuel-to-air ratio. As the vehicle is moving, an uncontrollable amount of air enters the throttle body and heads into the intake manifold. As such, the fuel has to be adjusted to be optimal for the amount of air. The mass airflow sensor measures the mass of the air that is entering the vehicle, and sends the information to the car’s computer management system. This system then controls the amount of fuel that is injected into the cylinders, so that the ideal fuel-to-air ratio is achieved. When the mass airflow sensor stops working, the computer cannot receive information on the air intake, and the fuel-to-air ratio will be wrong. This will cause your engine to run poorly, and sometimes not at all. It will also impact your gas mileage.
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