Fault code P2279 OBDII means that an air leak has been found in the intake manifold. This fault indicates that the amount of air entering the intake manifold is greater than the Manifold Absolute Pressure (MAP) Sensor.
The MAP Sensor, through a heated cable, tells the vehicle computer the amount of air entering the manifold, in addition to indicating the internal pressure of the manifold. The Engine Control Module (ECM) increases the temperature of the cable and maintains it, varying the voltage to the cable as air passes through. This voltage variation is interpreted as a signal of the volume of air.
The ECM makes adjustments for temperature changes, to do this, it relies on the information provided by the MAP Sensor. It makes adjustments to the injector timing to maintain an adequate air/fuel ratio. The Oxygen (O2) Sensor is also used to confirm and maintain this ratio. If the airflow is massive, the air temperature and the O2 Sensor have a large difference, this code is set.