Which National Emission Standard Vehicles Have Three-Way Catalytic Converters?
3 Answers
Regardless of the national emission standard, all vehicles are equipped with three-way catalytic converters. This is because newly manufactured vehicles must now meet the Euro 3 emission standards, hence they all come with three-way catalytic converters. Below is additional information: 1. Three-Way Catalytic Converter: The automotive three-way catalytic converter is the most important external purification device installed in a vehicle's exhaust system. It converts harmful gases such as CO, HC, and NOx emitted from vehicle exhaust into harmless carbon dioxide, water, and nitrogen through oxidation and reduction reactions. Since this catalytic converter can simultaneously transform the three main harmful substances in exhaust gases into harmless substances, it is called 'three-way'. 2. Working Principle: The working principle of the three-way catalytic converter is as follows: When high-temperature vehicle exhaust passes through the purification device, the purifying agents in the three-way catalytic converter enhance the activity of CO, HC, and NOx gases, promoting certain oxidation-reduction chemical reactions. Among these, CO oxidizes at high temperatures into colorless, non-toxic carbon dioxide gas; HC compounds oxidize at high temperatures into water and carbon dioxide; and NOx is reduced into nitrogen and oxygen. The three harmful gases are transformed into harmless gases, thereby purifying the vehicle exhaust.
I remember back in 2002 when I drove the company's Santana, veteran drivers were already talking about catalytic converters. In fact, vehicles meeting China II emission standards were required to have them installed, which means most cars around 2005 came equipped. This device, resembling an oversized honeycomb briquette, is mounted at the front section of the exhaust pipe, using precious metals to convert toxic exhaust gases into harmless substances. However, the technology was crude back then—leaded gasoline could easily poison and ruin the catalytic converter. It wasn't until China III and China IV standards vehicles adopted closed-loop electronic fuel injection that the system became truly reliable. Nowadays in the used car market, catalytic converters from China III vehicles are most frequently stolen, as the platinum and rhodium inside are often more valuable than the car itself.
I've been repairing cars for fifteen years and have seen all kinds of catalytic converters. Strictly speaking, even China I emission standard vehicles had experimental installations, but it was the China II standard implemented in 2004 that made them mandatory nationwide. Early catalytic converters were particularly delicate—using leaded gasoline by mistake or burning engine oil could clog them completely. By the China IV stage, the structure became much more complex, with dual oxygen sensors before and after the converter working with the ECU to precisely control the air-fuel ratio. The funniest thing is some China V vehicle owners remove the catalytic converter to boost performance, only to end up with the check engine light on and failing the annual inspection, with the modification costs enough to buy two new converters.
