Every bit of air that reaches the inside of your car passes through a single filter. When the cabin filter clogs, you notice it first with your nose and then with fogged windows — and most drivers connect neither to the filter.
What it does
The cabin filter cleans the air entering your ventilation system: pollen, road dust, soot, exhaust particles and, in activated carbon types, odours. It has nothing to do with how the engine runs. That is exactly why it is neglected: it never causes a breakdown, it just quietly gets worse.
How often it should be replaced
The common guidance is every 15,000–20,000 km or once a year, whichever comes first. Treat that as an average rather than a ceiling. Shorten the interval if you drive in:
- Heavy city traffic. In stop-start conditions your filter is cleaning the exhaust of the car ahead. In congested cities, 10,000 km is a sensible interval.
- Dust. Unpaved roads, construction zones and agricultural areas load a filter quickly.
- Pollen season, if you have allergies. Sneezing inside the car means the filter is either saturated or has never been changed.
Signs of a clogged filter
- Weaker airflow. The fan on full no longer moves the air it used to. This is the clearest symptom.
- A musty smell. A heavy odour the moment you switch on the air conditioning points to moisture and organic residue trapped in the filter.
- Windows clear slowly. Slow demisting means restricted airflow.
- A louder fan. More noise at the same setting means the blower is fighting a blocked filter.
Standard or activated carbon?
A standard particle filter traps dust and pollen. Activated carbon types additionally absorb gaseous pollutants and odours — exhaust fumes, sulphur smells, general city pollution. If you drive in dense traffic, the price difference pays for itself.
The step most people skip
Leaves and dust collect in the filter housing, and a new filter often goes in on top of them. Vacuuming the housing — and drying it if damp — measurably extends the life of the new filter. Check the airflow arrow printed on the frame too; fitted the wrong way round, a filter loses efficiency.
Wöbermann cabin filters are available in both standard and activated carbon versions for the vehicles most common on our roads.