The breakdown of a car involves all parts of the vehicle, and the situation is very complicated. Sometimes it is difficult to ascertain that the occurrence of faults depends on the quality of products. The malfunction of high reliability products is often easy to find, and the defective car, because of the use of material, processing technology and other reasons, the fault location is often very mental. If we use the method of failure probability analysis, it will be much easier to arrange in sequence.