9 Car Filters and What They Do

Filters play a crucial role in the performance of your vehicle. While most owners are familiar with air, oil, and fuel filters, there are several others that are equally important. Here’s a detailed look at nine types of filters you may find in a vehicle, along with their function, importance, and maintenance requirements.

engine air filter
Engine Air Filter

1. Air Filter

Function: The air filter cleans the air entering the engine by trapping dust, dirt, and other airborne particles.

Importance: Clean air is essential for proper combustion in the engine. A dirty or clogged air filter can reduce engine performance, increase fuel consumption, and cause higher emissions.

Maintenance: Typically replaced every 12,000 to 15,000 miles, but the interval can vary based on driving conditions and manufacturer recommendations.

2. Oil Filter

Function: The oil filter removes contaminants from engine oil, such as metal particles, dirt, and carbon deposits.

Importance: Clean oil is vital for lubricating engine components, reducing friction, and preventing wear and tear. A clogged oil filter can lead to poor engine performance and potential engine damage.

Maintenance: Usually replaced with every oil change, which is generally recommended every 3,000 to 7,500 miles, depending on the vehicle and oil type.

3. Fuel Filter

Function: The fuel filter screens out dirt, rust, and other impurities from the fuel before it reaches the engine.

Importance: Clean fuel ensures efficient combustion and prevents clogging of fuel injectors or carburetors. A blocked fuel filter can cause engine misfires, stalling, and decreased performance.

Maintenance: Replacement intervals vary widely but typically range from 20,000 to 40,000 miles. Always follow the vehicle manufacturer’s recommendations.

cabin air filter
Cabin Air Filter

4. Cabin Air Filter

Function: The cabin air filter removes dust, pollen, mold spores, and other pollutants from the air entering the car’s interior.

Importance: It ensures clean and healthy air for the passengers, improving comfort and reducing allergens.

Maintenance: Usually replaced every 15,000 to 30,000 miles or annually. More frequent replacement may be needed in areas with high pollution or for those with allergies.

5. Transmission Filter

Function: Found in automatic transmissions, this filter removes contaminants from the transmission fluid.

Importance: Clean transmission fluid is crucial for smooth gear shifting and longevity of the transmission components. A dirty filter can lead to poor shifting, transmission damage, and costly repairs.

Maintenance: Typically replaced every 30,000 to 60,000 miles, often during a transmission fluid change.

6. PCV Valve Filter

Function: Part of the Positive Crankcase Ventilation system, this filter removes oil vapor and other contaminants from the air before it is recirculated back into the engine.

Importance: It helps maintain proper engine ventilation and reduces harmful emissions. A clogged PCV filter can cause engine sludge buildup and reduce performance.

Maintenance: Generally inspected and possibly replaced during regular maintenance intervals, around 30,000 miles or as needed.

Diesel Particulate Filter
Diesel Particulate Filter

7. Diesel Particulate Filter (DPF)

Function: Found in diesel engines, this filter captures and stores exhaust soot to reduce emissions.

Importance: It is essential for meeting emission standards and maintaining air quality. A clogged DPF can cause reduced engine performance and increased fuel consumption.

Maintenance: Often includes a regeneration process to burn off accumulated soot. Replacement or cleaning may be required around 100,000 miles or as indicated by the vehicle’s monitoring system.

8. Breather Filter

Function: This filter, found in the engine’s crankcase ventilation system, removes contaminants from the air before it enters the crankcase.

Importance: It helps maintain clean air within the crankcase, reducing the likelihood of sludge and varnish formation on engine components.

Maintenance: Typically inspected during routine maintenance and replaced if necessary, often around 30,000 miles.

9. Hydraulic Filter

Function: Found in vehicles with hydraulic systems, such as power steering, this filter removes contaminants from the hydraulic fluid.

Importance: Clean hydraulic fluid ensures the proper functioning of hydraulic systems and prevents wear and damage to components.

Maintenance: Typically replaced every 30,000 to 60,000 miles, depending on the vehicle and system.

Review the owner's manual
Review your owner’s manual

Car Care Tips

Regular maintenance and timely replacement of these filters are essential to keep your vehicle running smoothly and efficiently, ensuring longevity and reducing the risk of costly repairs. We recommend familiarizing yourself with your vehicle’s owner’s manual and following the recommended maintenance schedule for each part.

See AlsoTransmission Care & Troubleshooting

Images under license from Adobe Photo Stock.

Matt Keegan
Author: Matthew Keegan
Matt Keegan is a journalist, media professional, and owner of this website. He has an extensive writing background and has covered the automotive sector continuously since 2004. When not driving and evaluating new vehicles, Matt enjoys spending his time outdoors.

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