K&N causing a CEL - 986 Forum - The Community for Porsche Boxster & Cayman Owners

bobdogwv · 07-05-2011, 05:30 AM

I purchased a brand new K&N filter for my 97. I was told that it was ready to go out of the box (pre-oiled from K&N). I installed it and after only about 30 miles of driving it threw a CEL. The codes were pointing to O2 sensors and such and also a MAF sensor. I took out the MAF cleaned it and reset the CEL, drove again a few miles and back on comes the CEL. I took out the MAF again, cleaned it and replaced the K&N with my original paper filter and guess what, no more CEL's. Should I clean my K&N and properly oil it to see if it was just over-oiled out of the box, or just replace my filter with a new paper one?

ekam · 07-05-2011, 05:47 AM

I've had K&N in my old car and it caused it to fail emission test. Put paper filter back in and it passed with flying colors, never K&N again.

They're in the same category as magnetic drain plug, if they're so good, why won't manufacturer put them in all their cars?

AndyA6 · 07-05-2011, 06:08 AM

Quote:

Originally Posted by ekam

I've had K&N in my old car and it caused it to fail emission test. Put paper filter back in and it passed with flying colors, never K&N again.

They're in the same category as magnetic drain plug, if they're so good, why won't manufacturer put them in all their cars?

I use K&N filters in my other cars and never had a problem. Too much oil out of the box will foul the MAF sensor.

bobdogwv · 07-05-2011, 08:00 AM

I think that I will probably just order a replacement OEM filter, I don't want any problems with the MAF. I have already noticed that now when I punch the throttle from a slower moving speed (20-25 mph) that there is a bit of a hesitation through 2nd gear but then goes away once I get up above 3K revs. I wonder if the MAF is still "dirty". Thanks for you help guys.

manolo · 07-05-2011, 09:33 AM

Never use a K&N straight out of the box. With very few exceptions they are almost always over-oiled from the manufacturer. I use them often, in many different vehicles and always clean them, wash them, let dry overnight and lightly oil them. They should be light pink when correctly oiled. If they are darkish/reddish/purplish or just plain wet, they are over-oiled.

I use one in my car and I've never had a MAF or O2 problem or any other related to the K&N. It doesnt surprise me at all that a new one straight out of the box caused a MAF problem.

shlim8 · 07-06-2011, 02:47 AM

This triggers a question (or concern..).

In fact I've used k&n on numerous other car and did not have any problems at all.

But I've read about the k&n filter for boxster and the problems it caused with the MAF. So this time around, I opted for a BMC filter, since there are a number of boxsters on BMC filters.

Frankly, the BMC and k&n filter looks similar in build and both uses oil on the cloth element, except the filters are different in color.

So why is it that a number of people recommend BMC ? Do they use a different kind of oil ? The construction doesn't look any different from k&n ?

Anyone ? Or will the bmc filter cause the same problems as the k&n ?

Brockmeister · 07-07-2011, 06:43 PM

I have K & N on all my vehicles except the 986. I just purchased the boxster last weekend. All of my vehicles like the K&N except my '04 BMW 325. It has the same symptoms all of you are describing. Once I cleaned the MAF the CEL went off and hasn't been back in a while. Maybe I'll try one in the 986 and see what happens