What is the Mass Air Sensor?

The MAS (or, in Mitsubishi speak, the MAF, or Mass Air Flow sensor) is a sensor unit in the intake of the car that calculates how much air is going into the motor. On the Mitsubishi motors (all Eclipses and Talons EXCEPT for 95-99 non-turbos), this is a Karmann Vortex sensor, which figures out how much air by watchting little vortices (swirls) in the air as it travels throught the sensor.

The sensor itself is a little teeny electrical thing, but it is housed in a sort of plastic tunnel that is filled with aluminum honeycomb. The honeycomb straightens the air so the meter can read it.