In the present paper, a complete literatures review of THERMAL BARRIER COATING applications in DIESEL ENGINE s is performed to select a proper type and to find coating effects. The coating system has effects on the FUEL CONSUMPTION, the power and the combustion efficiency, pollution contents and the FATIGUE LIFETIME of engine components. Usually there are several beneficial influences by applying ceramic layers on the combustion chamber, including the piston, the cylinder head, the cylinder block, intake and exhaust valves by using a plasma thermal spray method. Several disadvantages such as producing nitrogen oxides also exist when a coating system is used. In this article, all effects, advantages and disadvantages of THERMAL BARRIER COATING s are investigated based on presented articles.