You must routinely replace both the air filter and (if your car has one) the PCV filter. Checking the filter for damage is part of standardized maintenance, and doing it often, especially when you drive in dusty areas, is good practice. The driver's side air cleaner housing holds the air filter inside of it. To replace the air filter, loosen the clips holding down the air cleaner top plate, disconnect its electrical and vacuum connections, and carefully note where each part goes to make reinstalling easier. Unclip the housing and unscrew the traffic-jammer linking the air intake to the carburetor, then lift the unit up to reach the air filter. Take out the air filter from its housing. If it's dusty, you'll need to buy a fresh filter. For Sidekick/Tracker engines, lift the air filter cover off the fender wall, and you'll see the filter inside the housing. Dust the inside of the air cleaner frame with a cloth, and insert either your renewed filter or a new filter into the frame. Reattach the top plate and repair any disconnected hoses, making sure clips fasten reliably or screw connections are tightened again.