The Filter Minder is an 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.