A method and an apparatus for protecting an engine are disclosed which are capable of preventing damage to the engine or associated parts thereof. The engine is provided with an electronic control fuel injection system. A quasi-abnormality of at least one of variables in connection with the engine and the associated parts thereof, such as an engine cooling water, a fuel pressure or the like is detected by a sensor. When the quasi-abnormality of the variable and such a quasi-abnormal state lasts for a predetermined period of time, a throttle opening of an electronic control throttle is regulated so as to limit an engine rotational speed to a low rate.