The car engine should be fixed properly and meaning of the code P1491 Code is necessary to know. The powertrain of the car engine is defective and it needs fixing. The problem of the car engine can be fixed easily by automobile engineer using right meaning of the code. There are 2 main types of cylinder diffusion process used today what depends on the kind of engine. The engine P1491 code for the pushrod design which usages solenoids to modify the oil compression delivered to the lifters. In their collapsed state, the lifters are incapable to elevate their companion pushrods under the valve rocker arms, resulting in valves that cannot be activated and remain locked.