The manifold absolute pressure (MAP) sensor responds to changes in intake manifold pressure
(vacuum). The MAP sensor signal voltage to the PCM varies from less than 2.0 volts at idle to
more than 4.0 volts with the key ON and the engine OFF, or at wide open throttle (low vacuum).
The MAP sensor is used to determine engine vacuum level for other diagnostics, to determine
the barometric pressure (BARO) and to determine any manifold pressure changes while the
linear EGR flow test diagnostic is being run.
MAP Sensor Description And Picture