I know that MB says replace the activated charcoal filters at 60K miles, if your car is equipped with them. I'm ordering all of my filters for all of my MB's and I happened to pull the charcoal filters on my E500. They look new to me. Unlike the dust filter and engine air filter which show dirt, the charcoal filters do not. Is there any way to tell if you really need to change the charcoal filters? Or should I just take MB's word for it and do it. These are not cheap. Probably the most expensive of all of the car's filters at about 100.00.

I don't see how one could see the charcoal filter being at the end of life but it should not be from dirt or dust. On a W211 the charcoal filters aren't even used all the time but only when switched on from the control button or by the multifunction sensor at certain conditions. It could be that your filters have not seen air flow a lot. I assume the smog at big US cities isn't that significant that the filters would be turned on. Likely always on in most Chinese cities.

It is not obvious to me that the filter is bad after the specified mileage. Perhaps it needs to be changed more because it would be difficult to see if it has reach "end of life".

Yeah, I hear ya. I should note that I ALWAYS drive with the charcoal filter activated. Like you said though, I don't know if there is a way to see usage on these things.

That is interesting. The charcoal filters reduce air flow, but that isn't the reason I hardly ever use them. It is more because we really seldom have something to filter from the air (with the charcoal filter).

I keep them on mainly because I drive this car everyday in bumper to bumper traffic to and from work. I'm routinely behind school buses, dump trucks, tractor trailors, etc...

Plus, my allergies are completely out of control and I'll take all the help I can get as far as filtration goes.

how do we activate the charcoal filters?

Are you sure you did not forget a smiley? If not, then the answer is "change your old charcoal filters to new ones".

Hi Benz-O-Rama,

Where did you find the charcoal filters located? Are they under the dash board? Could you please specify how to remove them?

Thank you.

Passenger side footwell. There is a panel underneath the glovebox with 2 torx screws. Remove those screws and pull the panel down. Unplug the light connector for the footwell light and remove the entire panel. You will see two plastic sliders. Slide them and pull down on the pull tab. You'll see what I'm talking about once you get under there. When you pull that tab, the charcoal filter will come out. There are two of them there.

Kind of hard to describe it, but it's a 5 minute thing. Just take that panel off and it will become more clear to you.

Perhaps it was me missing the point, did you actually mean how to activate the mode where the air is filtered with the charcoal filter? This should only appear on a car with a 4-zone AC, not on all of those but there is a specific button to activate the function as in the attached figure (button number 9).

My new E550 is different. It has the four zone, but in place of the charcoal filter button (which my old '01 E320 had) it has a separate AC button there, which is supposed to turn off the AC (though I swear it still comes on sometimes even with the button and light off).

Any clue how to turn it on or off on the newer models. I don't recall seeing it in the manual.

I don't remember the date but I learned later models are "cost optimised" and have a combination filter also on the 4-zone models. Perhaps this is why your car does not have the switch.

Did ya one better.

W211 Under Glove Comp. Cover Removal.pdf


And for those that don't have the separate charcoal filter, but rather a combo filter look here:

This is also the place where the dust filter is located for those of us with the separate charcoal filters.

combofilterpix.pdf

Rama, thanks for the useful info. By the way, another way of stopping the exhaust fume from entering the car is to press the recirculating air button so you won't get the outside air into the car.

Yep, I use that alot. Problem is, it turns off after 15 minutes or something like that. Weird.

Activated carbon, also called activated charcoal or activated coal, is a general term which covers carbon material mostly derived from charcoal. For all three variations of the name, "activated" is sometimes substituted by "active". By any name, it is a material with an exceptionally high surface area. Just one gram of activated carbon has a surface area of approximately 500 m2, typically determined by nitrogen gas adsorption, and includes a large amount of microporosity. Sufficient activation for useful applications may come solely from the high surface area, though often further chemical treatment is used to enhance the absorbing properties of the material.

So it is activated by manufacturer with large surface area to allow for adsorption of airborne chemicals.

So that explains why you have it on all the time, I guess with air recirculation to trap airborne stuff from inside?

A pretty good explanation on the topic, thanks.

Can someone explain a little more?

Mine is the 4 zone climate control and I have the cover under the hood that looks exactly like what you guys refer to the combo filter but I also has the carbon filter button on the right most side on the panel!!??!!

Does that mean I have both?

Anyone has the pic of the actual filter?

Is that a sealed one piece like a housing with the charcoal inside?

Not sure if that's possible but can you replace the charcoal / active carbon inside the element?

Could always check it from EPC but your car must have the separate charcoal filters while the dust filter must have been changed to a combo filter when the car has been serviced. I'm not sure if the combo filter even would be the only spare part option today. More likely they only had the combo filter when most cars would use it and it also fits to your car.