What is the primary function of EGR (Exhaust Gas Recirculation)?

The primary function of EGR (Exhaust Gas Recirculation) is to recirculate exhaust gases back into the engine's intake. This process helps to reduce nitrogen oxide (NOx) emissions, which are a significant pollutant produced during combustion. By introducing a portion of the exhaust back into the intake air, the combustion temperature is lowered, which in turn reduces the formation of NOx.

While increasing fuel efficiency can be a secondary benefit, and reducing NOx can have a positive impact on overall engine performance, the primary role of the EGR system is focused specifically on minimizing harmful emissions. EGR does not filter engine oil nor does it boost engine power as its main function revolves around emissions control rather than direct power or oil management.