Yet another activated charcoal cabin air filter R&R DIY :) by bluebee

By diyauto
( 2 )

11 minute read

Yet another activated charcoal cabin air filter R&R DIY :)

Compliments of bluebee @


Yeah, it's incredibly simple, but, believe it or not, I actually had to peruse the "mit einbauanleitung" (=== includes mounting instructions") that came with my CUK2736-2 adsotop Mann "innenraumfilter mit aktivkohle" (=== cabin filter with activated charcoal) purchased from Autohauz (P/N: for $11.87 each ($23.74 for the set) with free shipping (because I added a dozen Mann $5.47 oil filters to bump the price over $50).

The new filter didn't look like the old filter (and it didn't have a one-way plastic tab), so I had to read the instructions that came with it.

Even then, I needlessly removed the cabin-filter housing spring clip and the three air-duct clips on the first of two exchanges.

So, I decided to write my own BMW E39 cabin-air filter DIY (if not for anyone else, at least for my own future reference).

NOTE: Also useful to remove air conditioning stink (see this thread).

Here goes ... (as always, please improve if needed).

Since summer is coming up, you should also check your two undercarriage drain hoses when you clean out the cabin air filter drains and replace the cabin air filters.

Otherwise, you may get the dreaded gym-sock air conditioning stink!

And, if you REALLY want to kill the gym-sock ac stink, drill an acess hole in your driver-side right-foot kick panel to spray disinfectant on the a/c evaporator cooling fins!

Then do the one-time set up of your AC controls, and you're set for summer!


Today, gunksny kindly posted a cabin air filter DIY PDF (e39 Cabin Filter DIY.pdf):

E39 Cabin Filter Replacement DIY

I added his link above just now to the bestlinks for future reference:

- How to DIY replace the activated charcoal cabin air filter (1) (2) & what cabin filter to buy (1) (2) & cn90's inexpensive cabin filter retrofit (1) (2) (3) & cabin air filter implications for stinky air conditioning (1) (2

For convenience, here are the pictures reproduced from that thread, only shrunken to 640x480 pixels:


It feels good to know, that, at least today, this (simple) DIY helped someone:

E39 (1997 - 2003) > Mann Cabin Filter Air Flow


Originally Posted by chelseafc 
Ok searched again after posting, found a bluebee post with this link, appears confirmation of arrow pointing up (as in towards the underside of the hood)

Of course, as simple as this DIY is, it isn't without controversy:


Originally Posted by edjack 
The air flows from top to bottom, and then into the car. Arrow points down. Ignore the writing.


Originally Posted by QSilver7 
The arrows on the microfilters should point upward...and Bluebee's as well as the other illustration confirms this.

Look again (closely) at the illustration...the air enters the microfilter compartment and flows UPWARD thru the filter, then the "fresh" air flows FROM the top of the microfilter into the car's HVAC system. The arrows near the microfilter are curved upwards to indicate that fresh air is drawn into the BOTTOM of the microfilter's plenum first...then UPWARD thru the micro & carbon filtering media, then into the car's HVAC fresh air intake. This allows HEAVY objects sucked into the plenum (or water) to fall to the bottom of the plenum otherwise it would have to fight gravity to enter into the system as the air is being drawn into the system. This is also why the water drains are at the bottom of the filter housing. If the directional flow was from TOP to BOTTOM then the filters would get soaking wet every time it rained or you washed the car: 


For the cross-linked record, these cabin air filters were suggested in this thread:

E39 (1997 - 2003) > Cabin Airfilter Replacement...


Originally Posted by Shrobby 
Not sure if anyone has found a good place for cabin air filters but I came across this..

Seems like a good place to get them....


I just accidentally realized a neat trick for helping get the cabin air filter housing back into the bimmer.

You can rotate left the snorkel on the side of the cabin air filter housing (and remove it if you need it out of the way).

Then, you put the cabin air filter housing back.

And, lastly, you rotate the snorkel back in place.


For the record, this was asked today:


Originally Posted by John Allen 
I purchased Fram air cabin filters for my 528. They have arrows on the side (edges) and the advisory "direction of air flow". It is not obvious to me which way the air flows. Can anyone advise whether the air flows up or down?

See also:

  • How to DIY replace the activated charcoal cabin air filter (1) (2) & what cabin filter to buy (1) (2) & cn90's inexpensive cabin filter retrofit (1) (2) (3) & cabin air filter implications for stinky air conditioning (1) (2)


Here's an exhaustive list of replacement cabin air filters from today:


Originally Posted by doru 
Below is a list with the equivalent charcoal activated cabin filters, exact fit for BMW e39. Just pick the cheapest, I think:

Air Qualitee AQ1055C
ATP CF-105 RA-60
Beck Arnley 042-2076
BMW OEM 64 11 0 008 138
Bosch C3821
Champ CAF1722
Fram CF10369
G.K. Industries CF1067
Hengst E960LC-2
Mahle LAK 73/S
Mann CUK 2736-2
Micron-Air BM97130C
Purolator C35509
TYC 800048C2

Personally, I used TYC for the last 5 years without an issue. Very good quality and very cheap.

EDIT: See also:

  • How to replace the activated charcoal cabin air filter (1) (2) (3) & what cabin filter to buy (1) (2) & cn90's inexpensive cabin filter retrofit (1) (2) (3)


This question came up today ...

E39 (1997 - 2003) > Air and Cabin filters.


Originally Posted by lsrguy98 
Can anyone tell me which brand air and cabin filters to get? Also, is the carbon activated filter a good way to go or are the paper filters best. Fram has all of the ones I need but not sure about the quality.



Originally Posted by QSilver7 
Get the one th as t looks li I e it will get the job done that it was designed to do...and fits your budget.

As far as activated charcoal or plain...again this is your call to make. Do you know what the actvated charcoal filters purpose is? It's to help filter odors from the fresh air entering the HVAC system. If that matters to you...then again it's your choice to make versus plain filter.


For cross reference, a related thread was opened today ...

E39 (1997 - 2003) > Cabin air filters


Originally Posted by gooddeal 
2001 BMW 530i 110k miles on the odom. Stale musty smell coming from the interior vents.
I suspect that the cabin air filters have never been changed. I am the 2nd owner.
Air conditioner is ice cold and works great.

open for suggestions..



Originally Posted by edjack 
The ducting needs hosing out with an A/C spray elixir intended to neutralize the smell. Remove the filters and spray the stuff into the ducts with the blower on low speed. Let it set overnight.

Get under the car and make sure the drain hoses are free. They are on either side of the trans.


Originally Posted by 540 M-Sport 
Replacing filters with new ones with activated charcoal will help, but most likely you have mold growing on the need to sanitize or clean it...there is an active thread right now on the subject in the E39 section. has a pair of Mann filters for $20...only problem is you need to buy $75 worth of stuff to get free shipping. But even if you pay for shipping that is the best deal going.


Originally Posted by gooddeal 
Thanks to all, I 'll replace the filters. I work for a BMW dealer so I get parts for 30% off.
However, I have an independent mechanic who will do the air conditioner cleaning..


See also:

  • How to replace the activated charcoal cabin air filter (1) (2) (3) & what cabin filter to buy (1) (2) & cn90's inexpensive cabin filter retrofit (1) (2) (3) & cabin air filter implications for stinky gym sock AC odors (1) (2) (3) (4)