How often should I replace the air filter on my Subaru?

For most Subaru models, the engine air filter is typically replaced around every 30,000 miles (48,000 km) under normal driving, while the cabin air filter commonly needs replacement every 15,000–30,000 miles (24,000–48,000 km) or about once a year. Exact intervals depend on your model year, engine type, and driving conditions, so always check your owner’s manual or with a Subaru dealer for your specific vehicle.

Driving conditions—such as frequent dusty roads, pollen-heavy seasons, or short trips that don’t allow the engine to heat up—can shorten filter life. If you notice symptoms like reduced engine performance, lower fuel economy, weaker HVAC airflow, or musty cabin odors, it’s a good idea to inspect the filters sooner and replace them if needed. Below are general guidelines to help you plan replacements.

Engine air filter: replacement schedule

Here's a quick, general guideline for engine air filter replacement by driving conditions:

• Normal driving conditions: Replace about every 30,000 miles (48,000 km) or as specified in your owner's manual.


• Dusty or harsh environments: Inspect around 15,000 miles (24,000 km) and replace as needed; typical replacement range is 15,000–30,000 miles depending on dirt load.


• Severe driving or performance concerns: If you notice reduced acceleration, lower fuel economy, or a visibly dirty filter, replace sooner rather than later.

Bottom line: Follow the schedule in your manual for your exact model and year, and use symptoms as a guide to adjust timing in dusty or high-pollen areas.

Factors that affect engine air filter life

Dust concentration, pollen, short trips, climate, and vehicle usage (for example, frequent stop-and-go city driving) all influence how quickly the engine air filter becomes clogged. In very dusty regions or during construction seasons, you may find yourself replacing more often than the standard interval.

Cabin air filter: replacement schedule

Here's a quick guide for cabin air filter replacement frequency:

• Normal driving conditions: Replace about every 15,000–30,000 miles (24,000–48,000 km) or roughly once a year, whichever comes first.


• Allergen-heavy or urban environments: Replace more often, typically every 6–12 months or every 10,000–15,000 miles, depending on conditions and odor sensitivity.


• Signs you need replacement sooner: Musty cabin odors, increased HVAC noise or strain, reduced airflow from the vents, or visible dirt on the filter.

In practice, many Subaru owners schedule cabin filter changes with annual maintenance, but in areas with heavy pollen, pollution, or dust, more frequent replacements may improve interior air quality and HVAC performance.

Signs your filters need replacement

Engine filters and cabin filters can both show telltale signs. For the engine, look for reduced power and fuel economy, or a filter that appears visibly dirty. For cabin filtration, pay attention to musty odors, dust on surfaces, or noticeably weak airflow from the HVAC system. If you notice any of these, inspect the relevant filter and replace if needed.

DIY vs professional service

Replacing both engine and cabin air filters is a common DIY task on many Subaru models and can save money on simple maintenance. Basic steps involve locating the filter housing, removing the old filter, inserting a correctly oriented replacement, and securing the housing. If you’re unsure about the exact procedure for your year and model, consult the owner’s manual or have a dealer/service center handle the replacement.

How to replace filters yourself (quick guide)

If you prefer to do it yourself, here’s a straightforward sequence to follow:

1. Engine air filter: Open the hood, locate the air filter housing, release the clips or screws, and lift off the cover. Remove the old filter, clean any debris from the housing, and insert the new filter with the correct orientation. Reattach the cover and secure the clips.


2. Cabin air filter: Locate the cabin filter housing (typically under the dash or behind the glove box). Remove the cover, take out the old filter, insert the new one with the airflow arrows facing the correct direction, and reassemble the housing.


3. Start the engine or turn on the HVAC to verify proper operation and no unusual noises or leaks.

Note: If you’re not comfortable performing either replacement, a quick visit to a mechanic or Subaru service center can handle both filters efficiently.

Summary

For most Subaru owners, engine air filters are commonly replaced around 30,000 miles, with more frequent changes in dusty or harsh environments. Cabin air filters usually follow a 15,000–30,000 mile window or about once a year, with more frequent replacements in areas with high pollen or pollution. Always verify the exact intervals in your model’s owner’s manual and consider environmental conditions and symptom indicators when scheduling replacements. Regular inspection and timely replacement help maintain engine performance and interior air quality.

Can I just clean my cabin air filter instead of replacing it?

Yes, you can clean a cabin air filter, especially if it's only lightly dirty or you are in a pinch between replacements, but it's not a substitute for regular replacement, as cleaning doesn't restore its original efficiency. For a deep cleaning, vacuum the filter and then rinse it with a low-pressure hose or a mild soapy water solution, making sure to let it air dry completely before reinstallation. 
Cleaning a cabin air filter

1. Locate and remove the filter: Check your owner's manual or online resources for the specific location, which is often behind the glove box. 
2. Remove loose dirt: Tap the filter to shake off large debris. Use a vacuum cleaner to remove as much loose dirt as possible. 
3. Clean the filter: 
   • Vacuum: Use a vacuum cleaner with a brush attachment to go over the filter's surface. 
   • Wash (for reusable filters): For a deeper clean, you can use a low-pressure hose to rinse water from the clean side to the dirty side. You can also soak it in a solution of soapy water for at least 10 minutes, then rinse it thoroughly with fresh water. 
   • Air dry: Allow the filter to air dry completely, preferably in the sun. Only reinstall it when it is fully dry. 
4. Reinstall: Place the filter back in the housing, making sure to orient it correctly according to any airflow arrows on the filter. 

When to replace instead of clean

• If the filter is heavily contaminated or heavily soiled. 
• If the filter is damaged or torn. 
• If the filter is a paper type that is not designed to be cleaned and washed. 
• If you notice reduced airflow, musty odors, or poor heating/cooling performance, it's best to replace the filter for optimal performance and air quality. 

What happens if you haven't changed your air filter in 2 years?

If you don't change your AC filter, it will begin to fail. It will no longer be able to filter the air properly, letting dust and contaminants get into the HVAC system. Dust jams the moving parts of an AC such as fan motors and valves.

How often should you replace the cabin air filter on a Subaru?

You should change a Subaru cabin air filter every 12,000 to 15,000 miles or once a year, whichever comes first. However, you should inspect it more often, especially if you drive in dusty conditions or have a history of allergies. Signs that it needs replacement sooner include decreased airflow, unusual odors from the vents, or excess dust in the cabin. 
This video demonstrates how to replace a cabin air filter in a Subaru Forester: 59sWorks IRLYouTube · Mar 3, 2021
Replacement frequency

• Standard interval: Replace every 12,000 to 15,000 miles or once a year. 
• Frequent driving: Replace more often if you drive in dusty areas, such as dirt roads or construction zones. 
• Check your owner's manual: For the most accurate information specific to your model, consult your Subaru owner's manual. 

Signs of a clogged filter

• Weak airflow from the climate control vents
• Unpleasant odors or smells coming from the vents
• Excessive dust or debris building up on your dashboard or other cabin surfaces
• Your defroster, heater, or A/C working harder than usual 

This video shows how to change the cabin and engine air filters in a Subaru Outback: 58sAutomotive Anonymous YouTube · Apr 4, 2024

How long does a Subaru air filter last?

12,000 to 15,000 miles
The frequency with which you should change your Subaru air filter can vary based on several factors, including driving conditions and environment. Manufacturer Recommendations: Subaru typically recommends changing the air filter every 12,000 to 15,000 miles.