Internal combustion engines are designed to meet the high power, low fuel consumption and also, low exhaust emissions. The engine running conditions is valid the concept that, the expectative is very high because of the variety of operating conditions like cold start, frequent start and stop, time high speed and load, traditional gasoline, mix of gasoline and alcohol and finally, alcohol fuel only.Considering such demand, this paper explains the relationship between the reliability bathtub curve, specifically the "Infant Mortality" portion. The bathtub curve describes failure rate as a function of time. The "Infant Mortality" portion of the curve is the initial section for which the failure (death) rate decreases with time (age). In general, these problems are related to manufacturing aspects or poor design definitions.With development of technology, hard failures, the ones that cause dependability, are becoming rare. On the other hand, soft failures, the ones that cause poor customer perception, are increasing with competition and customer high demand. This paper focuses on a literature review of these two categories, approaching firstly the mechanisms of failures and secondly, a short description of the basic concepts. Also, a special emphasis is given to engine noises.Throughout this discipline to understand the failure mechanism and then, the basic concepts, it is expected to: 1) concentrate on perfect systems, not perfect components, 2) understand interaction failure modes and finally 3) do not pack more functionality into one button just because you can, the paper discusses the relationship with engine typical failure modes. In addition, better advanced quality plans and control plans can be performed.