The P2018 OBDII fault code has to do with the value provided by the IMRC (Intake Manifold Runner Control) sensor. The location of this sensor is near the intake manifold. This device provides the PCM (Powertrain Control Module) with data that is used to control the air that will enter the engine according to the RPM (Revolutions Per Minute).
The DTC P2018 OBD2 DTC code setting occurs when the PCM encounters erratic or intermittent operation in the IMRC Sensor circuit.