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Tech Forum: Air & Cabin Air Filters


QUESTION: Which vehicles have cabin air filters?


ANSWER: Cabin filters have been used on some on Audis and other European makes since the mid-1980s, and on a growing list of domestic makes since the mid-1990s. Today, close to 80 percent of all new vehicles have one of these filters — or a place where one can be installed.
The best way to tell if a vehicle has a cabin air filter, or factory provisions for installing a cabin air filter, is to check the vehicle owner’s manual. Also check the catalog listings for cabin air filters by year, make and model.

If a vehicle has a cabin air filter, it will usually be located at the base of the windshield (open the hood and look in the cowl area for a small access door), or somewhere behind the glove box in the HVAC assembly (look under the dash for an access door). On some vehicles, the glove box has to be removed to access and replace the filter.


Most cabin air filters are flat panel filters, but some have unusual shapes so they will fit the HVAC inlet duct. Some may also be in two sections to make replacement easier.

Many motorists are not aware their vehicles have these filters. So ask your customers if they have checked their cabin air filters lately. It may stimulate some conversation as well as filter sales.

The service life of a cabin air filter depends on two things: the type of filter (dust or combination dust/odor) and operating conditions. A filter on a vehicle that is driven frequently on gravel roads will not have the life of a filter in a vehicle that is driven in a cleaner environment. Exposure to heavy traffic (especially diesel fumes) and urban pollution can also shorten the life of a combination dust/odor filter.


As a general rule, most cabin air filters should be changed every 20,000 to 30,000 miles — or more often depending on the size and capacity of the filter. Many vehicle manufacturers recommend replacing the filters every 12,000 to 15,000 miles or once a year. Refer to the vehicle owner’s manual for specific service interval recommendations.

Q: How often should other filters (air, fuel, oil & transmission) be replaced?

A: How often these filters have to be replaced depends on mileage, driving conditions and wear.
Changing filters regularly can significantly extend the life of the engine and transmission. Yet, studies show motorists are neglecting basic maintenance — and suffering the consequences as a result.


Recommended replacement intervals for air, fuel, oil and transmission filters can be found in the vehicle owner’s manual or scheduled maintenance chart.

As a rule, air filters should be inspected yearly (or more often if a vehicle is driven on gravel roads or operated in a dirty environment), and replaced every 24,000 to 50,000 miles, or as needed. If an air filter passes little light when a shop light is held behind it, the filter is dirty and needs to be replaced.

If a vehicle is having driveability problems that are due to low fuel pressure, the problem may be a clogged fuel filter. The fuel filter should always be replaced if the fuel pump has failed and a new pump is being installed.


The oil filter should be changed whenever the oil is changed. For the best protection, changing the oil and filter every 3,000 miles has long been a standard recommendation. Even so, many late-model owner’s manuals have extended oil change intervals of 5,000 miles, 7,500 miles or even higher. Some don’t even publish a service interval and instead use an “oil reminder” light to signal the driver when an oil change is needed.

As for transmission filters, many transmission experts recommend changing the fluid and filter every every two to three years or 30,000 miles — or once a year or every 15,000 miles if a vehicle is used for towing or other severe-service use. Many late-model vehicles do not even have transmission fluid or filter service intervals published in their owner’s manuals. Why? Because the fluid and filter last forever (just kidding!).


Actually, many late-model ATFs are capable of going well beyond 100,000 miles under “normal” driving conditions. The problem, though, is that many vehicles are not operated under normal-driving conditions but severe-driving conditions. Heat is very hard on transmission fluid, so the fluid may have to be changed long before it reaches 100,000 miles.

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