Red Seal Automotive Service Technician Practice Exam

What type of emissions does the EGR system aim to reduce?

1. Carbon dioxide emissions

2. Nitrogen oxide emissions

3. Hydrocarbon emissions

4. Particulate emissions

The correct answer is: Nitrogen oxide emissions

The EGR (Exhaust Gas Recirculation) system is specifically designed to reduce nitrogen oxide (NOx) emissions. NOx is a pollutant that contributes to the formation of smog and acid rain, and it is formed during the combustion process at high temperatures. The EGR system works by recirculating a portion of the engine's exhaust gas back into the combustion chamber. This process lowers the overall combustion temperature and consequently reduces the formation of nitrogen oxides. While carbon dioxide, hydrocarbons, and particulate emissions are important pollutants regulated by emissions standards, the primary focus of the EGR system is to combat nitrogen oxides. By understanding the function of the EGR system, it becomes clear why reducing nitrogen oxide emissions is its primary objective.