What are the primary components of vehicular emissions control systems?

The primary components of vehicular emissions control systems are indeed catalytic converters, exhaust gas recirculation (EGR) systems, and O2 sensors.

Catalytic converters play a crucial role in converting harmful pollutants in the engine's exhaust, such as carbon monoxide, nitrogen oxides, and unburned hydrocarbons, into less harmful emissions before they are released into the environment. This transformation is facilitated by a chemical reaction that takes place within the catalyst, which consists of precious metals such as platinum, palladium, and rhodium.

Exhaust gas recirculation (EGR) systems contribute to emissions control by recirculating a portion of the engine's exhaust back into the combustion chamber. This process lowers the combustion temperature, which helps reduce the formation of nitrogen oxides (NOx), a significant contributor to air pollution and smog.

O2 sensors monitor the amount of oxygen in the exhaust gases. They provide feedback to the engine control unit (ECU) to optimize the air-fuel mixture, ensuring efficient combustion and minimizing emissions. This feedback helps ensure that the engine operates within the ideal range for combustion, promoting cleaner exhaust.

The other listed components do not directly pertain to emissions control systems. Air filters and spark plugs are critical