09.07.2018 The Importance of the Cabin Air Filter

Cabin air filters can be found in the most inaccessible places, which could be the reason why they don’t always get replaced during a service. Corteco explores the importance of replacing the cabin air filter and looks at fitment instructions on a BMW 420.

Cabin air filters are an essential part of your vehicle and play a big role in keeping out harmful irritants. The role of a cabin air filter is to prevent dust, pollen and other pollutants from entering your car through the air conditioning and air vents.

It is recommended that you change the cabin air filter every 12,000 miles or at least once a year every time a vehicle goes in for its service. When it is time to change the filter you can rely on Corteco quality to protect you and your vehicle from irritants.


With the pollen season upon us it is vital that we get our cabin air filters checked on our next service – filtration is often overlooked due to the complexity of removing the filter from the car. They are often placed in obscure places or take a lot of work to remove and to install a new one. This can often be a misconception as most filters take between 5-10 minutes to replace and can be easily accessed by mechanics. 

Locate the position of the cabin filter under the glovebox case on the passenger side.

Remove two 10mm bolts from under tray and carefully unclip the retainers

Disconnect foot well lamp and 12v socket

Remove 2 10mm bolts from Cabin Filter housing within the heater box

Remove Cabin air filter and inspect for damage and contamination

With the cabin filter removed, it is a great opportunity to inspect inside for any leaves caught in the ducting, or ingress of dirt

Refit with new Cabin filter and build up in reverse order.

Once installed it is always a good recommendation to test the air con for noises and operation

Technician said “This was one of the easier cabin filters to change, not expected given the BMW are known to be more of a prestige mark. Often we find that the average family vehicle categories can have Cabin filters in obscure places, including under Fuse boxes or even behind Dashboards. This is likely the reason as to why many don’t bother to change them during a service. We would always replace them at each service as a matter of course unless our customers request us not to. This particular job has taken just under 10 mins to complete and is a major factor during a service.”

Andy Reynolds feedback- “With Health and welfare of vehicle occupants becoming more and more important within vehicle manufactures, often it is too easy to overlook those hidden parts that will prevent spread of germs and allergies, whilst also protecting occupants from the harmful gasses outside the vehicle. If a customer questioned the need to replace these Cabin filters, it is always advisable to consider the Health factors. For instance, should a driver use air conditioning on recirculation, potentially if a passenger has an allergy the recirculated air will always remain in the car, should a filter be blocked or collapsed, then this air will be contaminated, thus potentially affecting other passengers. Also the efficiency of the air conditioning unit will be affected with potentially blocked ducts.”

Cabin air filters are an integral part of every service. If they were not needed they simply would not be there. No matter how inaccessible they may seem, it should be explained to customers that the cost of replacement will far outweigh the cost in the future should it be ignored.


Head to http://www.corteco.com/en/products/filter/ to find out more about Corteco’s range of filtration products. Each filter comes with individual fitting instructions, advised timings. Further information of filter location can be found in our catalogue.


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