Air filters are among the easiest parts to replace yourself, and they are a perfect first DIY job for new BMW owners. A clean engine air filter helps the engine breathe, while a clean cabin filter keeps the air inside the car fresh. Here is what you need to know.
The two filters
- The engine air filter cleans the air before it enters the engine. A blocked filter can reduce performance and efficiency.
- The cabin air filter, also called the pollen or microfilter, cleans the air that enters the cabin through the ventilation system. Many BMWs use activated carbon filters that also reduce odours.
Both are listed in the BMW maintenance schedule. On many models, Condition Based Service shows when the cabin filter is due.
Finding the right part
Use your VIN or the exact model, engine and production date to find the correct filter in a parts catalogue. Filters from original equipment suppliers or reputable brands are recommended. Cheap filters may not fit properly or may filter poorly.
Some cars have two cabin filters or two engine air filters, especially larger models and V8 engines.
Typical locations
Locations differ between models:
- Engine air filter: usually in an airbox in the engine bay, held by clips or screws.
- Cabin filter: often under a cover at the base of the windscreen, under the bonnet, or behind the glovebox or footwell trim inside the car.
Search the forum for your model or look at the parts catalogue diagrams to see exactly where the filters are and how covers are fixed.
General steps
- Switch off the engine and remove the key.
- Open the cover carefully. Note the position of clips and screws. Take photos.
- Note the airflow direction printed on the old filter.
- Remove the old filter and clean loose debris from the housing with a vacuum or cloth. Do not let dirt fall into the intake.
- Fit the new filter in the same direction and make sure it sits correctly in its seal.
- Close the cover and check that all clips and screws are secure.
Common mistakes
- Forcing plastic covers and breaking clips. Use the right tools and patience.
- Fitting the filter upside down or in the wrong direction.
- Leaving gaps around the filter, which lets unfiltered air pass.
- Dropping screws into the airbox or ventilation ducts.
Share your experience
If you replace your filters, post a short guide for your model with photos and the part numbers. Simple, clear guides are among the most useful topics for new owners.