An internal combustion engine needs to mix approximately 10,000 litres of air with each litre of fuel to operate. Air enters the engine through the air filter. Without adequate air intake, the fuel mixture will be too rich in fuel, so it won't burn properly and the engine will run out of the oxygen it needs. Most manufacturers recommend replacing your air filter every 12,000 miles (approximately 19,000 km) or every 12 months, whichever comes first.
However, you should consider replacing your air filter more often if you live in an agricultural area or in any area with a lot of dust or impurities in the air. It's important to be aware of the signs that indicate your air filter needs to be replaced. A decrease in engine power is one of the most common symptoms. An inadequate supply of air can cause carbon deposits to build up in the engine, which will eventually activate the engine control light.
If the light comes on, check the air filter to see if it needs to be replaced before performing other diagnostics. Older vehicles with carburetor engines will have a significant drop in fuel economy when the air filter is blocked. Since a blocked filter restricts air flow to the inlet, the engine cannot achieve an adequate air-fuel ratio and, therefore, the efficiency of the internal combustion process is greatly reduced. Most modern vehicles with fuel injection engines will have a much less drastic drop in fuel economy.
In addition to air-fuel ratio problems, a clogged filter slightly reduces fuel economy by requiring the engine to work harder to draw air through the filter. Another symptom of the engine having difficulty getting air can be found when you step on the accelerator pedal. If the car moves forward and doesn't move as smoothly as you recognize, check the air filter more thoroughly for dirt buildup. This sign is very scary, but if the fuel doesn't burn completely before it leaves your car, truck, or SUV, you could end up with flames coming out of the tailpipes. This may look great on television and in movies, but this is a serious situation that needs to be resolved immediately. You don't want black smoke or flames coming out of your tailpipe, or your vehicle to be counterproductive.
Just as you can wheeze and gasp if you have a bad cold and your lungs are blocked, the engine can make its own unusual noises when deprived of the air needed to function properly. As long as you keep the filter clean and maintained, you'll avoid some of these easily preventable problems and extend the life of your vehicle. Many mechanics or dealers will allow you to buy the filter on your own and take it with them to do the installation. As a car owner, you should watch for the symptoms of a dirty air filter to ensure that your engine is kept free of debris. This makes it essential for your mechanic to check the air filter when you bring the car in for maintenance.
Often, it's enough to undo a couple of clips on the cartridge or air filter cover to inspect it. Dirty air filters prevent the system from receiving the right amount of air or fuel and make it difficult for the engine to perform its function. Once an air filter is too clogged and stops working, it can decrease the car's performance and even damage the engine. Keep in mind that even if there is no visible debris or dust on an inner layer of filter paper inside an air filter, it may still need replacing.