This external air filter is the primary intake element for the engine, removing airborne particulate before it enters the induction system. It mounts in the filter housing on the engine and is the first stage of air cleaning; any debris that passes through it would reach the inner safety element and, eventually, the turbocharger and cylinders. A restricted or damaged filter element reduces airflow, which causes a drop in engine power and an increase in exhaust temperature. The manufacturer machines the sealing surfaces to match the housing’s groove profile, ensuring the gasket seats fully so unfiltered air cannot bypass the element. On reinstallation, verify the housing latch is fully engaged and that no debris sits on the seal face.