Manifold Absolute Pressure (MAP) Sensor

The MAP sensor is mounted inside of intake manifold and measures changes in intake manifold pressure which result from engine speed and load changes. The PCM supplies a 5 volt reference signal and a ground to sensor and sensor outputs another voltage signal that is proportional to pressure signal. A high pressure (low vacuum) will produce a signal close to 5 volts and a low pressure (high vacuum) will produce a signal under one volt. The PCM scales MAP sensor signal in kilo-Pascals (kPa). The MAP signal is INVERSE of what is read on a vacuum gage. When MAP value is high, intake vacuum with a vacuum gage will be low. See Figure and Figure .

The PCM uses MAP information in conjunction with IAT information to determine density of air entering engine. MAP information is also used to determine barometric pressure and for ignition control. A faulty MAP sensor may cause various driveability conditions and should set a PCM Trouble Code.