By the manufacturer and model, the meaning of the B1578 Code is different. You need to know the model and manufacturer to get the correct meaning of the code. The meaning of code is also can be known by the dictionary meaning. The B1578 code checks engine lamp which is maybe the most worrying of lights since it could mean so many diverse things, from you did not screw the gas cap on tightly sufficient to look out for pistons flying over the hood and into the stratosphere. You need to solve the problem by the help of professional or auto repair center.