This car engine P3438 Code has some information what you need to use for solving the car engine. The car engine’s general problem is problem and some other problems what you can know by the study of the car engine code. Solve the car engine problem as fast as possible and in this case, you may take help from an automobile engineer. The possible causes of the car engine problems 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.