c63addix

So... ****! After 4 days of problem-free driving.. I finally got a CEL



Now I am quite sure it can't be any excess oil from the K&N air filters I installed because I patiently left them drying on paper towels for 1 day and a half (top and bottom). And even wiped them with a towel for 10 min before installing them into the car! Installation went very smoothly, better than the DIY video tutorial on youtube.

Ever since the 3rd night, i did a WOT about 160-180 km/h; the 4th day I suddenly got this CEL

Now, I don't get bothered by the CEL being on since some people say it might be our ECU adapting to the new filters. BUT, I am a bit worried if something really happened to the MAF sensors. The car isn't responding weird, acceleration still smooth, idle is fine and gas consumption is ****ty as usual.

Any tips on what I should do? Should I try to clean the MAF sensors or should I just wait a week to see if the CEL will go away? If I need to clean the MAF sensors, how do I remove them?

Thanks for the assistance !

Higgs Boson

It isn't oil on the MAF, the car just doesn't like the filters. I ended up throwing my KNs away and running stock filters with no charcoals.

My car would not shift right, would stumble, etc and get a CEL with the KNs. I guess they alter the MAF curve enough to affect the rest of the tune.

It's an easy fix if you know how to tune, I just don't have software for Mercs. :-(

ricecooker713

Check what the CEL is for before changing anything out. It could be anything, such as intake manifold gaskets causing selfadaptations dtc.

It can be the MAF sensors having oil on them, but you will see rough running and weird idle. If you clean them, just take them out and clean them with MAF cleaner, then clear the CEL

AMG9

Go back to stock and see if anything changes. If cell goes away then it's not the maf..

ZephyrAMG

I just don't get it...I have K&Ns with no problems....granted I didn't have charcoals but I just don't believe its the filter itself...so many people switched out filters with no problems...

Maybe the K&N is causing the engine to run more lean...

Clark Kent

I did mine charcoal delete + K&N filters first, then the tune later and have had zero problems - except tearin' up rear tires.

mthis

I run stock yellow paper filters they do the job well.
I ran K&N's before and way to much oil on them.

shades

I got AFE with no problems. The car is fine with aftermarket filters

hworang00

I have the AFE pro dry s and did a charcoal delete and swapped the filters out with no problems about 6 months ago. Haven't had a single problem. One thing that I was told to make sure was to make sure everything is seated correctly. It's easy to slide the filter too far one way or the other when closing the filter boxes and thus letting more air in than needed...I made sure to check the seals and made sure they were perfect....maybe try re-installing it?

Merc63

Did you clamp the intakes back onto the piping with no leaks?? A small leak after the MAF will cause a lean code as their is more air in the system than detected by the MAFs.

Or your intake manifold is leaking, which is really common.


An air filter is an air filter, it's not the problem. I run KNs with no problems.

c63addix

thanks for the assistance guys i think ill try reinstalling to make sure the seal is 100%. It was pretty hard to push the lid back into the MAF tube, maybe a small leak arose when i did a WOT

and almost 100% sure nothing to do with oil

stangxs

Same happened to me. I got the CEL after a couple days, re-checked the install made sure everything was sealed, and reset the light; came back after a day. I sent my ECU and told them I had filters installed, they incorporated it in the tune, and never got the CEL since (about a year now).

_timothy

i did a ROW swap with new filters at the same time and no check engine light 7 days later

c63addix

I reinstalled and made sure everything is sealed 100% and tight. Still got a CEL, if i take it to the dealer and tell them I installed K&N air filters will I be charged? Because on the K&N box it says clearly "will not affect car warranty".

I just want the dealer to reset it for me, unless anyone know how to reset the CEL?

Merc63

Get a cheap odb2 scanner, pull the code. It could have nothing to do with your AF, you're guessing. You can reset it too.

neoprufrok

Just got a CEL after the Weistec tune plus their filters as well.

c63addix

Great news, I didn't want to waste some money getting the odb2. Really cuz the car felt perfectly normal. To my surprise after patiently waiting 3 days the CEL went away. I'm guessing the ECU was just adapting to the new extra air flow? :s

Anyways this clarifies k&n air filters aren't an issue for our cars