Cause 1: The air filter is blocked.
 Remove the air filter to check whether there are dust, debris and other sundries inside. If there are any of the above phenomena, it can be confirmed that the air filter is blocked.
 Once the air filter is blocked, less air will be sucked in, and more fuel will enter, causing the phenomenon that the mixed gas is too rich.
 Solution 1: The cost of replacing the air filter element is about 400-600 yuan for the 4S shop and 200-300 yuan for the maintenance shop.
 Cause 2: oxygen sensor failure.
 Read the engine fault code with the special automobile detection computer, and analyze whether the working state of the oxygen sensor is normal through the data flow.
 The oxygen sensor is mainly used to detect the state of mixed gas. If the oxygen sensor is damaged, it cannot correctly obtain the state of mixed gas, resulting in the phenomenon of too rich mixed gas.
 Solution 2: Replace the oxygen sensor, and the 4S store will replace it free of charge during the warranty period. If the warranty is removed, the replacement cost of the 4S store will be about 1200-1800 yuan, and the cost of the repair shop will be about 800-1200 yuan.
 Cause 3: fuel injection nozzle failure.
 Read the data stream of the fuel injection nozzle with the special automobile detection computer, and analyze whether it is working normally. If it does not work normally, it will cause the fuel injection volume to increase, and the air entering is relatively small, so the mixed gas is too rich.
 Solution 3: Replace the fuel injection nozzle, and the 4S store will replace it free of charge during the warranty period. If the warranty is released, the replacement cost of the 4S store is about 1000-1500 yuan, and the price of the repair shop is about 600-1000 yuan.