Systems embedded in household electric appliances are used for long periods of time by various kinds of people. These environments sometimes cause unexpected failures. To save users from the appliances failures, every product is required to retain a high standard of quality and safety until their terminal period. We have developed a method named ESIM (Embedded System Improving Method) to extract the causes of failures and lead failure scenarios to make design specifications secure prior to development. The scope of the method covers hardware deterioration, partial failure, environmental exception, as well as illegal operations. In this article, we present a practical method to evaluate comprehensive failure scenarios derived from this method.