What are the exhaust emission standards for automotive environmental testing?
4 Answers
Automotive environmental exhaust emission testing standards specify that the limit for carbon monoxide is 6.3g/km, and the combined limit for hydrocarbons and nitrogen oxides is 2.0g/km. Automotive exhaust emission testing: The assessment is based on whether the smoke opacity value meets the standards, and whether the emissions comply with the standards is primarily determined by vehicle testing data. The smoke opacity value is used to confirm whether the vehicle meets the standards. Process of automotive exhaust emission testing: Computer entry of information, registration of vehicle details, and assignment of inspection lanes based on vehicle characteristics. Dispatchers will instruct staff to drive the vehicle to the designated inspection lane, during which dispatchers do not have the authority to change the inspection lane. The control room verifies whether the vehicle to be inspected has entered the correct inspection lane; without this confirmation, the next step cannot proceed. Exhaust emission testing is conducted by inspectors following prompts on the computer screen. Correct operation is essential for successful testing. The test results are compared with standard values, and then the results are uploaded to the server by the system. Finally, payment is made at the environmental testing fee counter. If the vehicle fails the test, it must undergo rectification before retesting. Vehicles that pass the test are issued an environmental certification mark.
Automobile exhaust emission standards vary across regions. In my area, repair shops commonly deal with the China VI emission standards. Simply put, during vehicle inspections, three types of substances are measured from the exhaust pipe: carbon monoxide, hydrocarbons, and nitrogen oxides must not exceed the limits. For example, small gasoline vehicles must not emit more than 0.5 grams of carbon monoxide per kilometer. Older vehicles have the hardest time meeting the standards, especially diesel vehicles, which often fail due to particulate matter levels. Inspection stations use the simple transient condition method, simulating acceleration and deceleration on rollers. If excessive emissions are detected, I usually first check if the three-way catalytic converter is clogged or if the oxygen sensor is faulty. If that doesn’t work, engine carbon deposits need to be cleaned. For vehicle owners, using standard fuel and regularly replacing the air filter greatly helps in meeting the standards.
Our testing station implements the latest China 6 emission standards, which are divided into Phase A and Phase B. Now, new vehicles must be equipped with an OBD system for real-time emission monitoring. The inspection mainly focuses on the concentration limits of hydrocarbons and carbon monoxide. There are significant differences between vehicle types: diesel vehicles are assessed for particulate matter indicators, while gasoline vehicles pay more attention to nitrogen oxides. Many places use the dual-idle speed method for testing, measuring exhaust emissions at 2500 RPM and idle speed. The most common reason for exceeding standards is catalytic converter failure. Replacing one can cost thousands of yuan, so it's better to perform maintenance in advance. We remind vehicle owners that modifying exhaust pipes or tampering with sensors is now strictly monitored. It's advisable to drive on highways before the annual inspection to burn off carbon deposits.
Last year, I finally understood the issue when my car failed the emission test. The current standard is China VI, which requires that the pollutants emitted per kilometer must not exceed the specified limits. For gasoline cars, the main test is the carbon monoxide content in the exhaust pipe. My old car was deemed unqualified if it exceeded 0.8%. The testing process only takes a few minutes—the technician inserts a probe into the exhaust pipe and revs the engine a few times. Later, I found out the oxygen sensor was faulty, and replacing it cost just over 300 yuan. Standards vary by city, with Beijing and Shanghai being particularly strict. For older cars, it's recommended to fill up with two tanks of high-quality gasoline and take a high-speed drive before the test to improve the chances of passing.
