Theory Of Operation
WARNING: This page is about a different car, the 2016 Dodge Durango. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module runs a diagnostic to check the MAP Sensor calibration and 5-Volt Supply circuit. It does this by reading the 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.