MAHLE cabin filters: clean air, safe driving

MAHLE cabin filters reliably supply the driver and passengers with clean air. They reduce dust on the dashboard and in the cabin, and avoid dangerous fogging of the windows. They also reduce the load on the blower and protect the HVAC system from contamination. Irreparable damage can occur to the air conditioning or heating system. The replacement intervals recommended by vehicle manufacturers should therefore always be followed. Rule of thumb: every 15,000 to 20,000 km. A regular sales driver for every repair shop.


Who's in the car, needs clean air to ensure a safe and concentrated participation in the traffic–and to feel comfortable. The air we breathe is, however, often loaded with harmful and allergenic substances and odors, which conventional filters can not eliminate.
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The demands on our cabin filters are pretty tough

The fan blows up to 100,000 litres of air into the cabin in one hour of driving. Without cabin filters, all kinds of pollutants, smog, ozone, exhaust gases, unpleasant odours, fine particulates, or pollen can enter the passenger cabin. The concentration of pollutants can be up to six times greater than at the edge of the road due to the differential pressure in the driving vehicle. Everyone knows what this means for the health, well-being, and concentration of the driver—which is why responsible manufacturers equip their passenger cars and commercial vehicles with cabin filters.

If the filter is not replaced on time, moisture builds up in the captured dirt. The filter becomes a feeding ground for bacteria and mould, which spread into the lines of the HVAC system, where they give off unpleasant odours and unhealthy emissions.

Lots of pollen and grass seeds—coarse contamination can lead to blockage of the pleated surface.

Soot and fine particulates have long ceased to be a problem.

Higher air humidity than in summer means more dust and other particles.

The filter is clogged and needs to be replaced.

Materials: for the safety of people, engines, and the environment—only the best

MAHLE Original and Knecht LAP prefilters are made either of polyester foam or polyester non-woven. The LAP is typically located upstream of the particle or combination filters and captures coarse dirt. This extends the service life of our cabin filters without (LA) and with activated carbon (LAK).

The polyester foam is resistant to ozone, hydrolysis, ageing, and temperatures up to 90°C, and is plasticiser- and CFC-free. The material is recyclable and can be easily incinerated. Our polyester foams have uniform pores that are created in a special process. We typically use foam materials of the class PPI 30 (pores per inch), as extensive lab testing has demonstrated that this pore size is the best compromise between service life and coarse particle separation.

Our non-woven mats made of polyester are non-flammable and resistant to hydrolysis, ageing, and temperatures up to 100°C. The material is free of silicone, plasticisers, and CFC, recyclable, and suitable for incineration.

Here are the filter classes in accordance with DIN EN 779:

Filter classSeparation level
G2Up to 80%
G3Up to 90%
G4> 90%

Combination filters: an activated carbon layer is embedded between two layers of non-woven. It captures hydrocarbons as well as inorganic and toxic gases such as hydrogen sulphide, sulphur dioxide, and nitrogen oxides, but also agricultural odours such as manure and fertilisers.

Activated carbon consists mostly of carbon (typically > 90%) with a very porous structure. The pores are connected to each other like in a sponge. Two grams of activated carbon contain approximately the surface area of a football pitch—a standard filter with about 200 g of carbon therefore has an filter surface area of about 100 football pitches.

As delivered: combination filter (LAK) made of an activated carbon layer sandwiched between two non-woven layers under the scanning electron microscope.

Cabin filter types and designs

There are particulate filters for coarse (LAP) and fine particles (LA) and combination filters (LAK) with an activated carbon layer. Coarse filters protect the filter surface of a downstream fine particle filter or combination filter against clogging with large particles. Particulate filters for fine particles protect against fine particulates, pollen, industrial dusts, and other tiny particles that can enter the lungs. Combination filters have an additional activated carbon filter—they absorb both odours and toxic gases such as nitrogen oxides as well as petrol and fertilizer fumes, and break down up to 99% of ozone.

MAHLE makes pure activated carbon filters that supplement conventional cabin filters for some types of vehicles. MAHLE deliberately avoids the use of solvent-based adhesives in the manufacture of its combination filters. The individual filter layers are bonded by heating.

Prefilter made of foam or non-woven

Research and development for the repair shop: so that you can continue to install safe products in the future

Innovative: commercial vehicle cabin filters for tapping out

For commercial vehicles that are used at construction sites or in quarries, the cabin filters also need to eliminate coarse dust. Under extremely high loads the filter should be replaced often—or it must be cleaned frequently, as in the case of the LA 43. It is installed by Mercedes-Benz as standard equipment in construction site vehicles from the Actros and Actros II series. It has a more robust design with strong aluminium side strips and solid plastic end strips. A fin on the end pleat of the non-woven and a foam seal all around the edge provide optimal sealing. The synthetic filter fleece is designed for a much higher dust retention volume and is supported and protected on both sides by a corrosion-resistant metal mesh.

The non-woven in the LA 43 is protected and supported on both sides by a grid.

The LA 43: robust design with side strips made of plastic (1) and aluminium (2) and a foam seal (3) all around.

Title: Cabin filter animation

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