This outer air filter is the primary element that removes airborne particulates before intake air reaches the engine's turbocharger and combustion chambers. It sits in the main air cleaner housing on the engine, and its pleated media captures dust and debris that would otherwise cause abrasive wear on piston rings, cylinder liners, and valve seats. A restricted or overloaded filter reduces airflow, which can cause a drop in engine power, increased fuel consumption, and visible black smoke under load. The original-manufacturer element is formed to the housing's seal profile, ensuring the gasket seats fully so unfiltered air cannot bypass the media. On replacement, clean the interior of the housing and verify the dust-ejection valve is unobstructed.