What are China 5 and China 6?
4 Answers
China 5 and China 6 refer to the emission standards for vehicle exhaust. These standards regulate the content of harmful gases such as carbon monoxide, PM, and soot emitted from vehicle exhaust. The higher the number, the more environmentally friendly the vehicle's exhaust emissions. The China 5 standard reduces nitrogen oxide and particulate emissions by 25% and 80% respectively, resulting in an overall emission reduction of 10% to 15% for China 5 vehicles. The China 6 standard is an upgrade to the China 5 standard, strictly controlling pollutant emission limits. Under the exclusion of operating conditions and test influences, the carbon monoxide emissions of gasoline vehicles are reduced by 50%, the total hydrocarbon and non-methane hydrocarbon emission limits are reduced by 50%, and the nitrogen oxide emission limits are tightened by 42%.
China 5 and China 6 are different stages of national emission standards for vehicles. I usually pay attention to environmental topics, and these standards mainly restrict pollutants in vehicle exhaust. China 6 is much stricter than China 5, for example, nitrogen oxide emissions are almost halved, and some new indicators have been added. Currently, major cities in China basically require new cars to meet at least China 6b standards, and even the transfer of older China 5 vehicles is affected. I remember that China 6 was implemented in phases starting from 2019. Initially, manufacturers were criticized for the increased costs, but it does help the environment. When driving a China 6 vehicle, you need to pay attention to fuel quality, as using lower-grade gasoline can easily trigger the malfunction indicator light, which is quite annoying.
I work in engine R&D, and China 5 and China 6 specifically refer to the GB18352.5 and GB18352.6 standards. The technical differences are significant. China 6 introduces real-world driving emission testing requirements and mandates the use of advanced OBD diagnostic systems. Starting from the China 6b phase, particulate matter (PN) monitoring is required, necessitating the installation of particulate filters. Simply put, it forces automakers to upgrade three-way catalytic converters and improve ECU programming. The most challenging part is the evaporative emission testing—now gasoline vehicles' fuel filler necks must be equipped with special devices. However, domestic automotive technology has caught up, and mainstream models can meet the standards, though maintenance costs have increased, especially for expensive after-treatment system components.
I once suffered a loss when helping a friend check out cars in the used car market. China 5 and China 6 emission standards directly affect vehicle circulation, with many cities restricting the transfer of vehicles below China 6. For example, if you want to buy a 2017 China 5 vehicle from another region, it can be transferred in Hebei but cannot enter Beijing. You can check the environmental protection label for specific judgment, and it's also noted on the registration certificate. Currently, China 6 vehicles are divided into 6a and 6b, and starting from 2023, all new vehicles nationwide must meet the 6b standard. When buying older cars, pay close attention to the emission standards. In some areas, China 3 and China 4 vehicles can't even enter urban areas, and they often fail the annual exhaust emission tests. It's best to go directly for China 6b vehicles to avoid hassle.
