Abstract: Buying durable goods, people not only concern about the quality and price of the product itself, but also concern about the services provided by the enterprise during the process of using the product. Extended warranty services could reduce the cost of repairing failure products and the risk of loss, but consumer need to pay for it. Also extended warranty services are considered as a very attractive marketing strategy that enhances product competitiveness, market share and brand value. The emotional utility of dissatisfaction or complain may be generated after purchasing the service. Because the failure is random, maintenance costs will be saved and the joy emotional utility will produce if failure happens; otherwise consumer will regret purchasing extended warranty service. So the emotional utility of the consumer will affect the effectiveness of the enterprise's implementation of the service strategy. Considering the influence of consumer sentiment, the duopoly differential game model was built to study the influence of the extended service strategy of the durable enterprise on the equilibrium price of the product, and further discuss the validity of the extended service strategy. The conclusion is that the input of the service is different in different ranges, and the equilibrium price of the product varies with the increment of the service investment. The equilibrium price of the extended service of the high quality product is proportional to the service investment, and the change of service price with the increasing of service investment is also related to the failure rate and extension period for inferior enterprise. The trend of the equilibrium price of durable goods is affected by the warranty period and the extension period, while show different characteristics with the service investment, failure rate and consumer utility change. For the inferior enterprises, the service investment to meet greater than 1, to increase the service investment to reduce the price difference with the high-quality products is effective, and it can achieve the same price with high-quality products to sell products. But only under certain condition, it is effective to extend the warranty period and the extension of the strategy to narrow the price difference with the high quality products. Finally, the rationality of the conclusion is further verified by numerical analysis. Discussing the effectiveness of extended warranty service strategies, this paper broadens the perspective of research on extended service, and also can provide decision support for the effective implementation of after-sales service strategy for durable goods enterprises.

Key words: emotional utility, inferior durable goods enterprises, extended warranty service, equilibrium price, effectiveness