The term "three-way catalyst" actually covers four different types, each with its unique coding identification on the casing. However, many car owners are not very familiar with this. So, how to interpret these coding labels to determine the type of catalyst? Next, I will provide a detailed explanation for everyone.

At present, three-way catalytic converters are mainly divided into four coding types: DOC, DPF, SCR, and ASC, each representing catalytic technologies with different efficiencies. Among them, DOC stands for oxidation catalyst, which is a relatively common type; DPF is a wall flow particulate trap, which has been widely used in multiple countries and vehicle models; SCR is a selective catalytic reduction technology typically used in conjunction with urea injection systems; ASC is an ammonia oxidation catalyst mainly used to eliminate excess NH3.

So, what do the letters on a three-way catalytic converter actually mean? In short, these letters are the identification of the type of catalytic converter. DOC stands for oxidation catalyst, DPF stands for wall flow particulate trap, SCR stands for selective catalytic reduction catalyst, and ASC stands for ammonia oxidation catalyst. Different vehicles need to be equipped with corresponding catalytic converters according to their emission characteristics to achieve the best exhaust treatment effect. For example, most trucks use SCR technology in conjunction with urea injection systems to effectively reduce harmful emissions from diesel vehicle exhaust. Nowadays, SCR technology is quite common in diesel vehicles.