The configuration of the DTC P2004 OBD2 code implies that the Intake Manifold Control (IMCR) is stuck in the open position.
The Powertrain Control Module (PCM) provides the IMRC with information related to current driving conditions. The IMRC relies on this data to regulate the amount of airflow that will be allowed into the intake system. With these intake airflow regulations, harmful emissions are reduced and a better air/fuel mixture is obtained. Besides, there is higher fuel efficiency.