[Working principle]The outside air into the throttle flow through the sensor, into the engine take away a very large part of the heat, the greater the flow of outside air, take away more heat in order to maintain the necessary temperature of the air flow sensor, it needs additional current to heat the sensor, it regulate the size of the air flow through the current. [Replace in Time]When your car shakily, acceleration is weak, fuel consumption increases, black smoke from the exhaust pipe, etc indicating that your mass air flow sensor needs to be replaced.Replacing the sensor improve fuel efficiency, assist the catalytic converter in better eliminating harmful gases from the vehicle's exhaust system, reduce emissions, and prevent premature catalytic converter damage. [NOTE]Please clean out the air box and replace the air filter before installating this Mass Air Flow Sensor Meter, or the Code and Check Engine Light may keep showing even if you replace a Mass Air Flow Meter Sensor measures the volume and density of air entering the engine, providing highly accurate airflow readings to the ECU over a wide range of ambient temperatures. Specification: Condition: Item Type: Mass Air Flow Sensor Manufacturer Part Number: A6110940048 72268400 6110940048 Fitment Type: Direct Replacement Fit for: For E-CLASS E200 E220 E270 E320 CDI W210 S210 S203 Material: Plastic colour: Black Package Contents: 2 x Sensor Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.