A clogged filter restricts airflow, which on a mass-air-metered engine shows up as reduced power and, on some vehicles, as a fuel trim fault rather than as an obvious loss of performance.
Panel and round filters are both listed, with dimensions and with the manufacturer part number. Two filters that fit the same housing can differ in media depth and in whether they are oiled, and an oiled filter on a vehicle designed for a dry filter can contaminate the mass air sensor.
Replacement intervals depend on where the vehicle is driven. A filter that looks clean at 30,000 miles on the highway can be loaded with fine dust at 15,000 miles on gravel.
The housing itself and its clips are listed under filter housings, because a housing that does not seal lets unfiltered air past the filter entirely.
