The engine P1556 Code is important thing and the powertrain problem is here the main problem. The deactivation of cylinders is realized by discharging a synchronizer pin what generally meshes the cam follower and rocker arms. The engine P1556 code resolutions the synchronizer pin that is unconfined using hydraulic compression which is measured by an enthusiastic solenoid. The fuel pump is the main problem and it needs to check to know the cause of the car engine problem. If you are not the perfect person to check or fix the car engine, you should not try to fix the car engine problem.