Patent ID: 8241413

Claim:
An air filter system of a motor vehicle, comprising: an air filter housing conducting an intake air flow, said air filter housing comprising a housing part of a moisture-sensitive plastic material; and an air passage section having an air flow course within conducting said intake air flow in an air flow direction, said air passage section including a passage wall extending in said air flow direction and circumferentially surrounding said air flow course along said air flow direction wherein said passage wall has an inner side facing said air flow course, wherein said passage wall of said air passage section is integrally formed of identical material on said housing part of said air filter housing; a mass air flow sensor arranged in said air passage section and operative to measure drawn-in mass air flow of said intake air flow; a plastic insert of a moisture-insensitive plastic material disposed on said inner side of said passage wall of said air passage section, said plastic insert including an enveloping circumferential wall arranged on said inner side of said passage wall and extending in said air flow direction, said enveloping circumferential wall circumferentially enclosing a flow cross-section through which said air flow course extends, said enveloping circumferential wall extending from a location upstream of said mass air flow sensor to a location downstream of said mass air flow sensor, said enveloping circumferential wall lining said inner side of said passage wall, separating said intake air flow in said plastic insert from said passage wall.