[Lou59]

2017 X3 Sdrive
40,000 miles

I received a card from my dealer saying teleservice had informed them I was due for service: oil change and microfilter.

I am willing to change the air filter myself. I looked on youtube for the how-to and aftermarket parts (autozone, advanceauto, napa, etc.) for the filter.

Air filter: https://www.autozone.com/filters-and...125p/10453_0_0

Cabin air filter: https://www.autozone.com/filters-and...30p/374713_0_0

The terms can be confusing. It seems that the dealer's postcard to me referencing the microfilter is for the filter that is below the glovebox. And this would be the filter for the cabin air.

Whereas the (engine) air filter is accessed under the hood and near the windshield on passenger side.

NOTE: Both of those videos are from FilterHeads.com and both are titled "How to Replace Cabin Air Filter 2017 BMW X3" and clearly it's two different filters.

Should I change both filters? I do not recall if either has been changed.

[Wgosma]

Yes, do both.

[WagonR]

I agree with Wgsoma, you should do both.

You listed 3 filters in your title, and there are 3 filters, to help clarify what they do and where they are:

1) Air filter, or engine air filter - as you can guess, this is the classic air filter that all cars have. It filters air going into the engine intake. The airbox for this is close to the engine and is under a lid that's screwed down with some torx screws.

2) Cabin air filter - this is the filter that is in the engine bay under the cowl up by the windshield on the passenger side. It's the second video you posted. When the HVAC pulls in air from outside of the car, it pulls it through this filter, so it's trying to keep crap out of the HVAC system.

3) Microfilter - this is the filter that's behind the glovebox. It's the first video you posted. This is a finer filter that's trying to filter out particulates in the HVAC system. I believe it's filtering air when you're either pulling air from outside, or if the system is on recirculate. This should help with smells or allergens or that type of stuff.

When it comes to replacements, I'd think about it this way:

1) Air filter - this is really based on how much crap your car tries to pull into the intake. This would generally be dictated by mileage, and not time, but if you lived on a dirt road or something like that, I'd replace more frequently. Otherwise every 30,000 miles would be reasonable.

2 & 3) Cabin filter and microfilter - these are probably more based on the time that they are used. Think of them like a furnace filter, they're keeping crap out of the HVAC system or out of the air the car pushes into the cabin. Time would play a roll in their effectiveness. I think 24 months is a normal replacement interval for them.

If you plan to keep the car for a while, FCPEuro is a good source for parts to look at. For stuff like this, the lifetime replacement warranty does provide some value.

[MSport_Jon]

I'm confused too. never seen the microfilter behind the glovebox and I have spent quite some time there.

I was under the impression that the cabin filter was the one inside the engine bay on the passenger side of the car.

Can anyone point out where this in-cabin microfilter is within the BMW ETK? i cannot find it for the life of me.

[rcblackwell]

Originally Posted by MSport_Jon

I was under the impression that the cabin filter was the one inside the engine bay on the passenger side of the car.

So was I! I'll be watching this post for follow-up.

[Wgosma]

Originally Posted by MSport_Jon

I'm confused too. never seen the microfilter behind the glovebox and I have spent quite some time there.

I was under the impression that the cabin filter was the one inside the engine bay on the passenger side of the car.

Can anyone point out where this in-cabin microfilter is within the BMW ETK? i cannot find it for the life of me.

see attached PDF.

[Lou59]

Big Thank You to WagonR!

Your explanation of the filters was very helpful.

[richardodn]

What doesn't help very much is that different sources use different terminology when talking about the same parts. I'll be repeating some of the above info and hope I can answer some of the remaining questions. All of this info is for US market cars.

Engine air filter - This is the filter responsible for cleaning the engine's air. It's typically mounted on or adjacent to the engine.

For the N55 engine, here are some part numbers
BMW 13717571355
Mann C28125
Mann C28125/1 (cold weather)
Mahle LX2525
Wix 49468

Other engines will use a different part.

Cabin main (or intake) air filter - The cabin main air filter is found on all F25 models. It's located below an access panel from the engine compartment. The panel is found on the cowl passenger side. From BMW, the filter came in two varieties; fine-dust filter and microfilter/activated carbon container.

US market BMW part numbers
Fine-dust filter
up to 09/2013, PN 64312452163
from 09/2013, PN 64319395930 (LCI)
Microfilter/activated Carbon container
up to 09/2013, PN 64312284828
from 09/2013, PN 64319312318 (LCI)

I honestly don't know what changed with the LCI. The housing themselves remained the same. Mahle specifies the same part for all years. As for other markets, you may want to verify the numbers.

Cabin recirculation air filter - This filter is only found on cars with automatic air (S534A=Yes). Its job is to filter the internal cabin air when the HVAC system is in recirculation mode. It's accessible through an access panel located at the top left rear of the glove box. It's a smallish panel not to be confused with the fuse box access panel.

US market BMW part number
Set of microfilters, recirculated air PN 64119237159

Service Intervals
For the engine air filter, I typically replace mine in the spring and fall. That's probably more often than needed, but Colorado can get a bit dusty. Brands I use are usually Mann, Mahle, Wix or Hengst. I don't bother with the "high efficiency" lifetime filters. In my opinion, a quality clean paper filter provides more than sufficient air for the engine.

For the two cabin filter sets, I usually replace them at the same time. I typically replace these annually, but every other year is likely fine. It really depends on your environment. I go for the activated charcoal versions to reduce odors. I usually find whatever is cheapest since I replace them annually.

[MSport_Jon]

So I decided to see if my X3 did in fact have a cabin recirculation air filter. Indeed, it is there where everyone else said it would be. Original BMW parts that were in there for 8 years...

The filter that was there was super filthy. The unit seemed to be made by Valeo and the Valeo part number is T905365 A01
BMW stamped part number is 64 11 9 251 118 9
The Valeo unit does not have a direction indicator but rather an "F" which I am assuming means "front" and if so then they meant the rear of the car as the F was closer to the rear of the car than it was to the front.

I could not find the Valeo part number on the web and neither did the BMW part number. Chances are they probably do not make ithem anymore.

I could not get the filters out by pulling out the plastic door above the glove compartment. It was much easier to remove the glove box entirely. Once I did that I was able to gain access to both access plastic panels instead of just one.

I changed it with a replacement filter made by BluePrint that cost me 10 dollars on Amazon. The BluePrint unit was much better than the Valeo unit and also had a mild germicide agent. If you do pull the glove box out. You do not have to bend the filter and compromise the shape to get it in the slot. The Blue Print unit does have an arrow.

[Wgosma]

Msport_Jon:
If you do the filters in future, try again w/o removing the entire glove box. I found it no real issue to change them after removing the small plastic cover. You can grab the old filters with needle nose if needed to remove.

[MSport_Jon]

Originally Posted by Wgosma

Msport_Jon:
If you do the filters in future, try again w/o removing the entire glove box. I found it no real issue to change them after removing the small plastic cover. You can grab the old filters with a needle nose if needed to remove.

Yeah... I did not want to do that. Notice how the last guy had to bend the filters to get them in... There were dust flow stains around the bezel of the filter which indicates that it wasn't seating properly. You cannot insert them in without bending them. By removing the glove box, I got them in there easily and without bending the frame of the filters or compromising their strength. It wasn't that hard to remove anyway. All is well.

[bmwPower99]

I bought mahle recirculation filters and they have an arrow stating " -> Airflow". Some instructions.state this arrow must point to the front of the car. I found that odd and believe that is wrong. The arrow should point to the back of the car. Attached you can see the leaf debris in the filter, this and other flint debris was facing the engine, the other side of the filter is clean. So air flow must be front to back.

[MSport_Jon]

Originally Posted by bmwPower99

I bought mahle recirculation filters and they have an arrow stating " -> Airflow". Some instructions.state this arrow must point to the front of the car. I found that odd and believe that is wrong. The arrow should point to the back of the car. Attached you can see the leaf debris in the filter, this and other flint debris was facing the engine, the other side of the filter is clean. So air flow must be front to back.

I was taking a look at TIS and it does not mention anything regarding the direction the recirc filters should be installed. The design looks like it calls the airflow from the inlet grills inlets, right above the filter installation lids. These inlets are facing the rear of the car and already filtering at that point before the air gets into the systems and out the dash vents. I think the arrows should face forward. Please remember that these are secondary filters that are used in case you decide to recirculate your cabin air. If you do not, then the filters inside the engine bay are used. Please see picture.

[bmwPower99]

Originally Posted by MSport_Jon

I was taking a look at TIS and it does not mention anything regarding the direction the recirc filters should be installed. The design looks like it calls the airflow from the inlet grills inlets, right above the filter installation lids. These inlets are facing the rear of the car and already filtering at that point before the air gets into the systems and out the dash vents. I think the arrows should face forward. Please remember that these are secondary filters that are used in case you decide to recirculate your cabin air. If you do not, then the filters inside the engine bay are used. Please see picture.

Thanks for the info. The Mahle filters go in and out like butter compared to the valeo so it will be easy to flip. I'm just confused as to why all the debris was caught on the side facing the engine.

[richardodn]

These are the filters for the recirculation system. They never see outside air directly.

[MSport_Jon]

Originally Posted by bmwPower99

Thanks for the info. The Mahle filters go in and out like butter compared to the valeo so it will be easy to flip. I'm just confused as to why all the debris was caught on the side facing the engine.

Yeah that is strange. mine were filthy on both sides but the side facing the rear of the car was even more so.

[smckinney87]

Originally Posted by richardodn

What doesn't help very much is that different sources use different terminology when talking about the same parts. I'll be repeating some of the above info and hope I can answer some of the remaining questions. All of this info is for US market cars.

Engine air filter - This is the filter responsible for cleaning the engine's air. It's typically mounted on or adjacent to the engine.

For the N55 engine, here are some part numbers
BMW 13717571355
Mann C28125
Mann C28125/1 (cold weather)
Mahle LX2525
Wix 49468

Other engines will use a different part.

Cabin main (or intake) air filter - The cabin main air filter is found on all F25 models. It's located below an access panel from the engine compartment. The panel is found on the cowl passenger side. From BMW, the filter came in two varieties; fine-dust filter and microfilter/activated carbon container.

US market BMW part numbers
Fine-dust filter
up to 09/2013, PN 64312452163
from 09/2013, PN 64319395930 (LCI)
Microfilter/activated Carbon container
up to 09/2013, PN 64312284828
from 09/2013, PN 64319312318 (LCI)

I honestly don't know what changed with the LCI. The housing themselves remained the same. Mahle specifies the same part for all years. As for other markets, you may want to verify the numbers.

Cabin recirculation air filter - This filter is only found on cars with automatic air (S534A=Yes). Its job is to filter the internal cabin air when the HVAC system is in recirculation mode. It's accessible through an access panel located at the top left rear of the glove box. It's a smallish panel not to be confused with the fuse box access panel.

US market BMW part number
Set of microfilters, recirculated air PN 64119237159

Service Intervals
For the engine air filter, I typically replace mine in the spring and fall. That's probably more often than needed, but Colorado can get a bit dusty. Brands I use are usually Mann, Mahle, Wix or Hengst. I don't bother with the "high efficiency" lifetime filters. In my opinion, a quality clean paper filter provides more than sufficient air for the engine.

For the two cabin filter sets, I usually replace them at the same time. I typically replace these annually, but every other year is likely fine. It really depends on your environment. I go for the activated charcoal versions to reduce odors. I usually find whatever is cheapest since I replace them annually.

Sorry to revive a dead thread. Thank you for providing PNs!! I reached out to BuyBMWPartsDirect’s customer service email and was told their technicians state there is no other filters aside from the main air filter and the cabin filter under the hood. Didn’t seem right. I opened up the glove box and lo and behold there are the filters I was trying to order from them.

[FloridaNative]

I believe the micro filter behind the glovebox is only to filter the recirculating air. When using fresh air, it goes through the cabin air filter at the base of the windshield. I think.

I pulled my micro filter and it looked brand new so I put it back in. Cabin filter was filthy and so it got changed obviously.

-Mike

[Qsilver7]

Just an FYI...not sure if this applies to your models...but on the 5/6/7/8/X5/X6/X7...the fresh air intake into the HVAC system not only goes through the course air filter in the engine bay...but also flows through the interior microfilter. And so does the recirculated air within the cabin. It also gets pulled back through the recirculation/microfilters since we bring pollen/dust/dirt into the cabin with us or when we open a door or window.

The illustrations below shows how fresh air and recirculated air flow through the course filter in the engine bay (blue) & the microfilters below the glovebox (yellow/orange) for the 5/6/7/8/X5/X6/X7: