The data is used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel metering for optimum combustion (see stoichiometry) and influence the advance or retard of ignition timing.

The MAP sensor can also be used in OBD II (on-board diagnostics) applications to test the EGR (exhaust gas recirculation) valve for functionality, an application typical in OBD II equipped General Motors engines.

Note: Carburetors are largely dependent on air volume flow and vacuum, and neither directly infers mass.

With OBD II standards, vehicle manufacturers were required to test the exhaust gas recirculation (EGR) valve for functionality during driving.

The way they do this is during a deceleration of the vehicle when there is low absolute pressure in the intake manifold (i.e., a high vacuum present in the intake manifold relative to the outside air) the powertrain control module (PCM) will open the EGR valve and then monitor the MAP sensor's values.

If the EGR is functioning properly, the manifold absolute pressure will increase as exhaust gases enter.

Vacuum-Boost sensors can display negative readings, indicating vacuum or suction (a condition of lower pressure than the surrounding atmosphere).

At sea level one can convert boost to MAP by adding approximately 100 kPa.