Theory Of Operation
The Powertrain Control Module (PCM) runs a diagnostic to check the Manifold Absolute Pressure Sensor (MAP) calibration and 5-Volt Supply circuit. It does this by reading the Barometric Pressure (BARO) when the engine is not running. The BARO reading with the engine off should fall within a predictable threshold. If the reading is below this threshold when the monitoring conditions are met, it is determined that the 5-Volt Supply was lost or the MAP Sensor is out of range.
NOTE:
Do not use shop air to clean out the MAP Sensor when diagnosing a MAP Sensor related fault as this will cause internal damage to the sensor.