What are China III and China IV Vehicles?

[SanRemington]

China III and China IV vehicles are motor vehicles that comply with China's automotive emission standards. The following are the key differences between China III and China IV: 1. China III refers to the third stage of China's automotive emission standards, which introduced upgrades and modifications to engines and exhaust systems to reduce pollutant emissions, including enhancements to vehicle self-diagnostic systems. 2. China IV represents the fourth stage of China's automotive emission standards, featuring further upgrades to the post-emission treatment systems compared to China III, with pollutant emission standards reduced by 50% to 60% relative to China III. 3. To stably meet the China III emission standards, vehicles must be equipped with technical measures that ensure pollutant emissions comply with China III standards, along with the use of fuel that meets Euro III standards.

[SamuelRose]

My neighbor Lao Wang talked to me about this last week when he sold his China III pickup truck. China III and China IV refer to different phases of the national vehicle emission standards. The China III standard was implemented in 2007, and China IV was an upgraded version enforced in 2011. They have completely different limits on pollutant emissions from vehicle exhaust. For example, China IV vehicles are required to emit 30% less carbon monoxide than China III vehicles, with stricter controls on hydrocarbons and nitrogen oxides. In some cities in North China, China III vehicles are now banned from entering urban areas. For instance, that diesel truck spewing black smoke at the entrance of our neighborhood is a typical China III vehicle, which was fined three times last year. When buying a used car now, you must check the environmental label. Some older vehicles, even if modified for emissions, still can't meet the China IV standard.

[DiWalker]

I remember during the 2015 vehicle inspection, my 2008 sedan almost faced driving restrictions due to its China III emission standard. Simply put, China III vehicles were produced under emission regulations established in 2005, while China IV vehicles are products of the 2010 updated standards. The most noticeable difference lies in the exhaust treatment systems - China IV models generally come with OBD diagnostic systems and more sophisticated three-way catalytic converters. Last month, a friend at the auto parts market disassembled two engines: China III vehicles only have one oxygen sensor, while China IV models have at least two. Currently, vehicles relocating to the Yangtze River Delta region must meet at least China IV standards. It's quite troublesome to transfer a China III vehicle across provinces. For refueling, it's best to go to major gas stations, as substandard fuel can trigger the malfunction indicator light even in China IV vehicles.

[MacArthur]

Having worked as a car mechanic for ten years, the main difference between China III and China IV models lies in the engine electronic control system. Most China III vehicles use open-loop control, while China IV models are upgraded to closed-loop control with self-diagnostic functions. For example, in terms of nitrogen oxide treatment, China III engines rely solely on EGR (Exhaust Gas Recirculation), whereas China IV engines must be equipped with a DOC (Diesel Oxidation Catalyst). Last week, while helping a customer inspect a 2012 China IV SUV, I noticed its onboard computer could store up to 20 fault codes, compared to a maximum of 5 for China III vehicles. Currently, the Beijing-Tianjin-Hebei region prohibits annual inspections for China III diesel vehicles, while gasoline vehicles can still hold on for another two years. Friends buying used cars should remember to check the Vehicle Conformity Certificate, which clearly indicates the emission standard.

[MacJameson]

Yesterday I accompanied a friend to look at used cars. The dealer pointed at a 2010 Sylphy and claimed it was China IV compliant, but actually the rear badge showed GB18352.3-2005, which is China III certification. Emission standards are determined by the vehicle model certification year, not production year. The key difference lies in control strategies: China III vehicles mainly rely on engine tuning for exhaust treatment, while China IV vehicles must be equipped with post-processing devices. Taking catalytic converters as an example, China IV vehicles have 50% thicker precious metal coatings than China III, with three-way catalytic efficiency reaching 98%. In the Pearl River Delta region, China III diesel trucks have been banned from operating 24/7 since 2023, and restricted zones for gasoline vehicles are also increasing.

[AlexisDella]

Having worked at the vehicle inspection line of the DMV for five years, the most intuitive way to identify is by looking at the emission standard sticker color. National III vehicles have yellow stickers, while National IV vehicles have green ones. The key difference lies in the exhaust emission limits: National IV vehicles have a 30% lower carbon monoxide emission limit compared to National III, with an even greater reduction in hydrocarbons. I recall that after the system upgrade in 2018, all National III vehicles had to be tested using the dual idle speed method, while National IV vehicles underwent the stricter simple transient cycle method. Currently, some southern cities have included National III gasoline vehicles in their environmental traffic restrictions. Last year, an old Santana I handled couldn't be transferred because of this. I'd advise extra caution when buying cars over 15 years old—many so-called 2007 models are actually rebranded National II vehicles.