The possible causes of the car engine P3440 Code are Low oil pressure, Restricted oil passage, Engine mechanical condition, Faulty Cylinder Deactivation Solenoid, Cylinder Deactivation Solenoid harness is open or shorted and Cylinder Deactivation Solenoid circuit poor electrical connection. You need to know the reason of the car engine problem if you want to fix the car engine problem. Otherwise, you need to check the car engine and fix the problem by the car technician. However, do not drive the car with the car engine problem. Any serious problem may trigger in the car engine due to use the false meaning of the car engine code.