The primary function of the EGR system is to reduce what?

The primary function of the EGR (Exhaust Gas Recirculation) system is to reduce nitrogen oxides (NOx) emissions from the engine. By recirculating a portion of the exhaust gases back into the intake manifold, the EGR system lowers the combustion temperature in the engine. High combustion temperatures are a key factor that contributes to the formation of NOx emissions, as nitrogen in the air can combine with oxygen at elevated temperatures to form these harmful compounds.

Incorporating exhaust gases, which contain less oxygen than fresh air, effectively dilutes the intake air charge and results in the combustion of a fuel-air mixture that occurs at a lower temperature, thus reducing the formation of NOx. This makes the EGR system a critical component for meeting emissions standards and reducing the environmental impact of gasoline engines.

While other options like carbon monoxide (CO), hydrocarbons (HC), and carbon dioxide (CO2) are also pollutants resulting from combustion, the EGR system specifically targets NOx emissions as its primary function.