The symptoms of automobile failure have different characteristics because of different causes. In conclusion, there are roughly the following conditions: 1. The mutation of the working condition of the working condition is the sudden abnormal phenomenon of the working condition of the car, which is a common symptom of failure. For example, when the engine is suddenly flameout, it is difficult to start again, or even can not be started; the engine has a sudden reduction in driving power and a powerless driving; the sudden brake failure or deviation or even failure during the driving. The symptom of this kind of fault is obvious, so it is easy to detect. 2, abnormal sound of the car during the running abnormal noise, is the car fault "alarm". When a driver suddenly realizes a strange noise, as a driver should be aware of the car's problems, he should immediately stop the car and check the car. 3. Exhaust smoke is abnormal. The main components of normal combustion products during operation are carbon dioxide and a small amount of water vapor. If the engine does not burn properly, the exhaust will be mixed with unburned carbon particles, hydrocarbons, carbon monoxide and a large amount of steam. In addition, there are nitrogenous compounds and so on. At this time, the color of the tail gas may turn black, blue or white, that is to say, exhaust smoke is abnormal. For gasoline engines, normal exhaust should have no obvious smoke. However, when the lubricating oil moves on the cylinder, the exhaust gas is blue. When the combustion is incomplete, the exhaust gas is black, and the tail gas is white when the oil is mixed with water. 4, overheating often occurs in engines, transmission, drive axle, main reducer, differential and brake assembly. For example, the engine overheating, most of the cooling system is a problem, is the lack of coolant or pump does not work; the transmission and driving bridge overheating, most of the lack of lubricating oil; brake overheating, most of the brake shoe does not return to position. These phenomena can be directly reflected by the dashboard warning lights. They need to be observed when driving, or the temperature of the exterior can be tested by hand. 5, leakage leakage refers to the leakage of fuel, lubricating oil (or gear oil), brake fluid (or compressed air) and oil liquid of power steering system. This is also obvious symptoms of failure, careful observation can be found. For example, when the compressed air leaks, it can clearly hear the sound of leaking. 6, excessive consumption of fuel and lubricating oil and lubricating oil indicates that the technical condition of the vehicle has deteriorated and malfunction has occurred. 7. In the operation of a car with special odor, such as brake lag, clutch slip and other faults, it will emit the coke of the friction plate; when the engine is overheated and the lubricating oil channeling is burned, it will diverge and send out a special smell; the circuit short circuit and the iron lap lead will also be burnt and burnt. 8, the automobile appearance abnormal car is parked on the flat site to check the appearance condition, such as the phenomenon of lateral or longitudinal skew, that is, the appearance of abnormal appearance. Most of the reasons are car frame, body, suspension, tire and other failures, which will cause unstable direction, deviation, center of gravity transfer and wheel "eat tire" and other failures.