Normally, the life of spark plugs is 15000 km, and the life of long lasting spark plugs is not more than 30000 km. However, many car owners' spark plugs often have problems like this, which do not meet their normal service life. Actually, the working temperature of the spark plug is quite high. When the engine is running normally, the temperature of the insulator of the spark plug is generally between 500 and 600 degrees Celsius. Too high or too low temperature has no effect on spark plugs. When the spark plug temperature is too low, the insulator on the spark plug is easy to accumulate carbon, resulting in leakage of electricity, resulting in a lack of fire. If the spark plug working temperature is too high, it will cause early ignition and engine knock. In the Chery automobile training camp, the staff of the exclusive store concluded two common failures of spark plugs. One is the serious erosion of the spark plug, the other is the sediment of the spark plug. The spark plug should be replaced when the spark plug is found to have scars or damage at the top of the spark plug, and the electrode appears to be melted and ablated. During the replacement process, the vehicle owner can check the signs and color changes of the spark plug ablation. Symptom 1: electrode melting and insulator white diagnosis: this phenomenon indicates that the combustion chamber temperature is too high. This may be too much Coke in the combustion chamber, resulting in too small valve clearance, further causing overheating of the exhaust valve or poor working of the cooling device. When the spark plug is not tightened according to the prescribed torque, it will also cause electrode melting and insulators appear white. Symptom 2: the electrode circle and the scar diagnosis of the insulator: This indicates that the engine is early ignited, which may be caused by premature ignition or low gasoline octane value and high heat value of spark plugs. Symptom 3: diagnosis of insulator tip fragmentation: Generally speaking, detonation combustion is the main cause of insulator breakdown. The ignition time is too early, the gasoline octane number is low, and the combustion chamber temperature is too high, which may cause the engine knock combustion. Symptom 4: a gray and black streak at the top of the insulator: the appearance of this stripe indicates that the spark plug has been leaking, and the owner needs to replace the new piece unconditionally. The spark plug has a sediment spark plug. The top of the insulator and the electrode sometimes deposit on the sediment. The owner of the car should not look down on the sediment. In severe cases, the engine may not work properly. After cleaning the spark plug, the vehicle can be operated normally for a while, but similar situations will occur shortly. In fact, the deposit of spark plug is only a surface phenomenon, which may be a sign of problems with other parts of the vehicle. Symptom 1: there is an oil deposit diagnosis on the spark plug: when the oil deposit appears on the spark plug, it indicates that the lubricating oil has entered the combustion chamber. If there are oily deposits on individual spark plugs, it may be caused by damage to the valve stem oil seal. But if the spark plugs of each cylinder block are adhered to this sediment, it appears that the cylinder is leapt. Generally speaking, when the air filter and ventilation device are blocked, the cylinder is prone to jump oil. Symptom 2: Black sediment diagnosis on spark plugs: spark plug electrodes and internal black deposits, usually indicating excessive concentration of mixed gases in the cylinder. The owner can increase the speed of the engine and continue for a few minutes to burn a layer of black soot on the electrode.