When is the right time/mileage to change those 2 micro-filter elements under the hood, right in front of the bottom of the windshield. I took mine out last week and tried to clean them. They looked very dirty !!

 

lcc014:
Mine came up for replacement 2 years after my manufacture date. The service indicator showed brake fluid and mirco-filters were due - right at two years.

 

Exactly like mine, brake fluid and micro-filters right at two years.

 

I would not recommend cleaning these filters. They come new with an electrostatically charged layer to capture dirt/pollen and a activated carbon layer to capture smog/gases/bad odors.

Over time the electrostatic performance drops off, but the built-up dust acts as a filter itself. Also, the carbon pores become clogged. Cleaning will not solve these problems - you should replace the filter at the recommended interval. If you suffer from allergies, you should replace more frequently. In short, these filters are not "cleanable"

 

Is micro air filter replacement covered under the free maintence service from BMW?

 

YES.

 

Thanks for all the responses. I "cleaned" them by meant of turning them upside down and then shaked them hard to remove most of the dust/leaf on it.

 

ZinMe:
The micro-filter and the brake fluid replacement were both covered by the maintenance agreement - no cost.

 

Good to know-- thanks.

 

Hi lcc014:

What I meant to convey in my prior posting was that the filter, when "cleaned" actually has worse filtration properties than when dirty, as long as it hasn't reached its useful life where it becomes clogged and the pressure drop because critical.