How often should the air and cabin filters of BMW cars be replaced?

[SanEliza]

According to the maintenance manual of BMW cars, the air filter should generally be replaced every 10,000 to 20,000 kilometers or every other maintenance interval, while the cabin filter should be replaced every 10,000 kilometers or approximately once a year. It is recommended to inspect both the air and cabin filters during each maintenance service. The location of the car's air filter varies depending on the intake design and engine structure, typically situated in the air filter housing on the engine intake pipe. The cabin filter is usually installed beneath or inside the glove compartment on the passenger side, with some models placing it below the windshield in front of the passenger seat. The cabin filter and air filter in a car are different components, serving distinct purposes. Air Filter: A type of filter, also known as an air cartridge or air cleaner, primarily used in engineering vehicles, automobiles, agricultural machinery, laboratories, sterile operating rooms, and various precision operation rooms. During operation, the engine inhales a large amount of air. If the air is not filtered, suspended dust particles can enter the cylinders, accelerating wear on the piston assembly and cylinders. Larger particles entering between the piston and cylinder can cause severe cylinder scoring, especially in dry and sandy working environments. There are two types of air filters in cars: dry and wet. Dry filters are made of paper or organic materials, while wet filters are made of metal mesh. The function of the air filter is to remove particulate impurities from the air, ensuring that clean air enters the cylinders and preventing dust from being drawn into the engine, which could accelerate wear on the piston assembly and cylinders. Cabin Filter: The cabin filter is installed in the car's air conditioning system and can absorb fine particles, reduce respiratory discomfort, minimize irritation for allergy sufferers, and protect the air conditioning cooling system. Without the cabin filter, these particles can enter the cabin, contaminating the air conditioning system, reducing cooling performance, and causing allergic reactions, lung damage, or irritability due to ozone exposure, all of which can affect driving safety. Cabin filters are generally divided into two types: standard cabin filters and activated carbon cabin filters. Standard cabin filters are typically made from a specific eco-friendly filtration material processed and folded into a single-layer white structure. Activated carbon cabin filters consist of non-woven fabric layers sandwiching fine activated carbon particles, which are then further processed into the filter. Dirty Air Filter: Using a heavily soiled air filter while driving can restrict engine airflow, leading to incomplete fuel combustion, unstable engine performance, reduced power, and increased fuel consumption. Therefore, it is essential to keep the air filter clean. The car's air filter is a device that removes particulate impurities from the air, composed of one or more filtration components. Its primary function is to filter harmful impurities from the air entering the cylinders, reducing early wear on the cylinders, pistons, piston rings, valves, and valve seats. Thus, air must pass through the air filter's fine filtration before entering the cylinders. A dirty air filter can cause poor engine performance, excessive fuel consumption, and engine damage. If inspection reveals minimal dust and light clogging, the filter can be cleaned using compressed air blown from the inside out and reused. Severely dirty air filters should be replaced promptly. Dirty Cabin Filter: A dirty cabin filter can become clogged with impurities, reducing airflow from the air conditioning system and impairing cooling performance. It can also increase fuel consumption, generate noise, and shorten the lifespan of the car's air conditioning system. Residual impurities on the cabin filter can breed bacteria and mold, posing health risks to passengers and potentially causing serious illnesses.

[StKate]

I remember in my BMW-driving circle of friends, we often talk about cabin air filters. As an experienced driver, I think this thing is just as important as an air purifier. If it gets dirty and isn't replaced, the air in the car feels stuffy, and when you turn on the AC, the air carries a dusty smell that can easily make you cough and feel uncomfortable. According to the official BMW manual, it's recommended to replace it every 12 months or every 15,000 kilometers driven, but it depends on your driving environment—like me, driving daily in congested city traffic with heavy air pollution, I replace mine every 10 months or so. It's cost-effective and gives peace of mind. I also recommend going to a 4S shop or authorized service center for a check-up, and while you're at it, get the AC ducts cleaned to prevent bacteria growth and avoid allergy flare-ups on long drives. Personally, I think it's not worth saving on this small expense—replacing it early makes for a much better driving experience.