The rocker arm actuator provides hydraulic pressure to the Variable Valve Timing (VVT) System. This allows the VVT system to make the necessary adjustments to the valve.
The Powertrain Control Module (PCM) uses the rocker arm actuator oil pressure switch to verify that the oil pressure is adequate so that the VVT System can operate without any problems.
In case the PCM finds a resistance level in the rocker arm actuator circuit that indicates it is stuck in the on position or open, the DTC P2647 OBD2 will be set.