Understanding the MPX2053 Pressure sensor
This sensor is a differential sensors, it does not measure absolute pressure but  measures the pressure applied VS the ambiant atmospheric pressure.

Depending the package you can also have another "pipe" with a specific pressure.

From the datasheet:


  Voltage Output versus Applied Differential Pressure The differential
  voltage output of the sensor is directly proportional to the
  differential pressure applied. The output voltage of the differential
  or gauge sensor increases with increasing pressure applied to the
  pressure side relative to the vacuum side. Similarly, output voltage
  increases as increasing vacuum is applied to the vacuum side relative
  to the pressure side.


Also Figure 4 on the datasheet shows the vent hole at the bottom and can see the piezo (Die) is between the pressure applied and ambiant pressure.



So the if you apply 120kPa and the ATM Pressure is 101kPa it will measure 19kPa.

If you want to measure the absolute atmospheric pressure, this is not the right sensor to use.