The car engine code P2551 DTC reports a sensor false or replacement of the device what is improbable to resolution the original problem. The error is most possible to be instigated by the organizations that the sensor is managing, but might even be formed by the cabling to the sensor itself. The leak detection pump is part of the evaporative productions organization. This method tests the fuel scheme to make sure what is not leaking fuel vapors into the air. The system pulls a void on the fuel system and holds it for a specific period of time. Know the code more from online.