The MAF sensor (Mass Air Flow) is located in the intake air stream, and is responsible for measuring both the flow and the density of air entering the engine. The PCM (Powertrain Control Module) uses this reading together with other parameters of the sensor, with the objective that the supply of fuel is guaranteed, so that, at a given moment, there is an optimum power and the fuel efficiency is the necessary one.
The DTC code P0101 gives us to understand that there is a problem with the Mass Air Flow Sensor (MAF) and that the PCM has detected that the frequency signal of this sensor is not within the necessary range, which should be default of the value that has already been calculated by the same MAF sensor.