Manifold Absolute Pressure Sensor

The Manifold Absolute Pressure (MAP) sensor measures changes in intake manifold pressure which result from engine load and speed changes. It converts these to a voltage output.

A closed throttle on engine coast down produces a relatively low MAP output. MAP is opposite of vacuum. When manifold pressure is high, vacuum is low. The MAP sensor is also used to measure barometric pressure. This is performed as part of MAP sensor calculations. With ignition ON and engine not running, powertrain control module (PCM)/engine control module (ECM) will read manifold pressure as barometric pressure and adjust air/fuel ratio accordingly. This compensation for altitude allows system to maintain driving performance while holding emissions low The barometric function will update periodically during steady driving or under a wide open throttle condition. In case of a fault in barometric portion of MAP sensor, PCM/ECM will set to default value.

A failure in MAP sensor circuit sets a diagnostic trouble code P0107 or P0108.