Editor's Note: In this limited series Under the Hood, we'll share do-it-yourself tips for drivers who want to wrench their own cars, no matter their skill level. What\u2019s one thing you and your car have in common? You both need to breathe. While engines don\u2019t have lungs, they do require a steady supply of air to power the combustion that keeps them running. Modern cars \u201cbreathe\u201d through an intake system that features an air filter, which catches dirt and dust before it enters the motor, where it can cause damage. As you might imagine, over time, the filter gets dirty. Changing the filter will promote better airflow into your engine and keep it clean\u2013and it\u2019s one of the simplest automotive maintenance jobs you can do. When you change yours, it\u2019s a prime opportunity to check your vehicle\u2019s hoses and belts for wear. Locate Your Air Filter and Remove the Cover First, grab your car\u2019s owner\u2019s manual and pop the hood of your vehicle. Consult the manual to find the air filter assembly in the engine bay. The location will vary between vehicles, but it's likely a large plastic box with a large-diameter hose extending from it and into the engine. Undo the plastic clips or loosen the screws that secure the cover. You might also need to unlatch the hose or unplug some wiring to remove the cover and access the filter. (Pro tip: before removing any components or hardware, take a picture of the air filter area so you can later put it back together to match the pic.) Assess Its Condition and Replace (Purchase the following supplies from eBay Motors or your retailer of choice.) Once you\u2019ve removed the cover, you should be able to see the air filter itself. Remove it and hold it up to a bright light to assess its condition. If it\u2019s covered in a heavy layer of dirt and light doesn\u2019t pass through easily, it\u2019s time to replace it with a new one. You can opt for a paper filter (the cheaper option) or a reusable one that you clean at set intervals (pricier but creates less waste). Whichever you choose, make sure you purchase one that will fit your specific car\u2013auto part shops, and most online marketplaces will provide a way to search for the exact part you need. Put the new filter into the air filter housing, making sure you place the correct side facing down. Then replace the cover, use the screws or clips to secure it, and reattach any hoses or wiring you unplugged. Your new air filter is now installed, and your engine can breathe easier once more. Check Hoses and Belts Don\u2019t close the hood yet\u2014you should check your main hoses and belts, too. In addition to connecting your air filter to the engine, hoses also run to and from your vehicle\u2019s radiator and heater. Visually inspect these hoses for cracks, bulges, or fraying, and give them a squeeze. They should be firm with some give; if they feel brittle, spongy, or mushy, that\u2019s a sign of wear. Mark damaged hoses with a marker or colored tape. Also, with the engine off, inspect any belts, which are usually located on the front or side of your engine and connect a series of pulleys. Look for cracks, exposed threads, or separation between belt layers. Another sign of a bad belt: squealing or chirping noises when this e engine is running. (Also, see whether these belts have noticeable slack; if so, they may need a simple tightening. This is a relatively simple job, too, but will require other tools and specifics noted in a repair manual or a mechanic.) Make a note of anything that looks amiss with your belts\u2013 don't put tape on them to mark wear. When you bring your car in for service, you can show your mechanic any worn hoses or belts to see if they need to be replaced.