The symptom of automobile failure, also called fault phenomenon, is the concrete manifestation of the fault. It is helpful to the cause of failure and the diagnosis of the part, and help the driver to take corresponding measures according to the specific situation. A mutation of the working condition is called the sudden abnormal phenomenon of the car's work situation. This is a common symptom of fault. It is usually sudden and should be dealt with calmly. It is common: it is difficult to start the engine suddenly after the engine is suddenly flameout, and the engine is suddenly driven down in driving, making the driving powerless, the sudden brake failure or deviation and so on. We should pull the car aside and recommend it to the maintenance department without any experience. Two, abnormal sound of sound can cause abnormal sound of automobile engine or chassis part, should be seriously treated, otherwise it is easy to cause machine accident. Experience shows that all heavy noises and obvious earthquakes are malignant faults. They should be stopped immediately to find out the cause. In general, the sound often has different characteristics due to different causes. When judging, it should be carefully examined and correctly distinguished. Three, overheating phenomenon, usually in the engine, transmission, drive axle and brake assembly. Normally, no matter how long the car works, the total Chengdu should be kept at a certain temperature. Except for the engine, if you touch it with your hands, it will feel hot and painful. That means it is overheated. The overheating of the engine indicates that the cooling system is caused by problems, such as detonation, early combustion, weak driving and even burning accidents, if not eliminated in time. Four, leakage of the leakage of the usually even fuel, lubricating oil, cooling water, brake fluid and the steering system oil and so on, this can not be ignored, once found should be immediately eliminated, otherwise it will cause overheating, burning, and so on. Five, the smoke color is not normal for the gasoline engine, the normal exhaust gas should be no obvious smoke, when the cylinder oil fleeing, the exhaust gas is blue; when the combustion is not complete, it is black; when the oil is mixed with water, it is white. Diesel engine exhaust is abnormal, often accompanied by engine inability or inability to start. Six, runaway or tremble is mainly caused by incorrect alignment of front wheels, unbalanced crankshaft or drive shaft, etc. Seven, fuel consumption is generally abnormal because of poor engine operation or improper chassis adjustment. Oil consumption is too much, in addition to the cause of leakage, most of the engine is malfunction, often accompanied by a large number of smoke or pulsating smoke at the oil intake, and the exhaust color is not normal. The main reason is that the gap between the piston and cylinder wall is too large or has serious wear. Eight, there is a special smell that often occurs when the brake is dragged and the clutch is skidding. When the engine is overheated or the oil is burned, a special smell will be sent, and the scent of the tie wire is destroyed when the circuit is short circuited. Once the vehicle is detected, it should stop to find out the problem. Nine, the abnormal appearance of vehicles is caused by abnormal movements such as frame, suspension, tire and so on. It will cause unsteadiness of direction, running deviation, shift of center of gravity, wheel eating fetus and so on. These symptoms are very easy to detect, and the exclusion should be solved as soon as possible. If not, we should also contact the repair factory for comprehensive procuratorial work.