To know the right meaning of the engine code is found from the car manufacturer and it is important thing to know the right meaning. The engine P0064 Code is found in the car engine manual. Do not use general meaning of the code for solving the car engine problem. Deactivation of cylinders is achieved by freeing a synchronizer pin that generally interlocks the cam follower and rocker arms. The engine P0064 code resolves the synchronizer pin is unconfined using hydraulic compression which is measured by a dedicated solenoid. Do not drive the car, until you get the car engine is ok.