What should I do if the automobile exhaust test is unqualified?

If the automobile exhaust is unqualified, you can clean the three-way catalyst and oxygen sensor, clean or replace the spark plug, and thoroughly clean the engine. These three methods are described in detail below: 1. Cleaning the three-way catalyst and oxygen sensor: the first thing that comes to mind is that the engine mixture of the three-way catalyst and the front oxygen sensor is not fully burned, which will produce a large amount of carbon deposit, which will attach to the inside of the three-way catalyst and the surface of the oxygen sensor with the exhaust pipe. Therefore, cleaning the three-way catalyst and oxygen sensor will solve many problems of unqualified automobile exhaust. If there is something wrong with the added engine oil, the sulfur, lead and phosphorus contained in the engine oil will cause three-way poisoning, leading to the poisoning failure of the three-way catalyst. This kind of fault needs to be replaced, and cleaning with oxalic acid solution can restore activity. 2. Clean or replace the spark plug: the failure of the ignition system such as the spark plug and the high-voltage bag will also lead to the car exceeding the standard. Spark plug is the most vulnerable part, and poor working condition of spark plug will increase emission pollution. Spark plugs are also easy to deposit carbon, which can be recovered by sandpaper cleaning or cleaning with cleaning agent, and the ignition gap can also be adjusted. However, if the spark plug fails to ablate or reaches its service life, it is necessary to replace it with a new spark plug with better performance, so that the working condition of the engine will be much better and the exhaust emission will be improved. 3. Deep engine cleaning: If the three-way catalytic converter is cleaned and the spark plug oxygen sensor is replaced, the automobile exhaust emission is still not up to standard. On the premise of eliminating the faults of sensors such as air flow meter and temperature sensor, it is necessary to do a major maintenance to clean up the carbon deposit in the engine. Cleaning the carbon deposits in the throttle valve, oil circuit, air intake and fuel nozzle in the engine will also improve the working condition of the engine and avoid the problem of increased emission pollution caused by poor engine working conditions such as incomplete combustion of mixed gas.