Air filter service indicator that monitors air filter restriction and indicates when the air filter should be serviced. As the air filter gets dirty, the yellow position indicator moves in the clear window of the service indicator and locks at the highest point. It can be read even after the engine is turned off. The air filter should not be cleaned until the yellow position indicator reaches the red zone. Reset the position of the indicator to zero by pushing the yellow reset at the end of the service indicator.
Air filters typically plug very slowly, and initial filter restriction may not occur until 50,000 miles or more depending on operating conditions. Diesel applications and off-road use will generally require more frequent cleanings or maintenance.
Most applications will show no air filter restriction on the service indicator with a new K&N Air Filter. There may be rare instances where the position indicator could move in the window even with a new air filter. This could result from high air flow engine requirements, or from operating in high humidity or rain. Do not be alarmed if the clean air filter restriction exceeds the initial calibration of the service indicator. The air filter should not be cleaned until the yellow position indicator reaches the red zone.
K&N Air filters become more efficient at stopping dirt as they build a dust film. It is recommended that the air filter be cleaned only when the air filter service indicator reaches the red zone.