I had a K&N CAI on my car and I went through 2 MAFs. K&N swears their filters don't damage MAFS but after i went to a "Dry" Filter i had no more issues.

 

It fouled your MAF on the first install ( out of the box)? or after your first cleaning? I've have a filter on my Toyota truck for over two years and one cleaning my me with no problems. It is imparitive that you just LIGHTLY oil the filter and then let it dry before you re-install.
If it fouled th MAF on the initial install then I would worry.

 

does anyone sell it preassembled?

 

The K&N CAI is pretty much assembled when you get it and the install is very easy. Takes maybe 10-15 minutets

 

oh.. how come the TS and others are complaining about how its a pain in the *** to assemble it? so it comes ready to intall then?

 

RobbC, is your MAF backwards? SG993 had his in the right way.

On my K&N, the cord must go the opposite direction for proper measurement. You might want to doublecheck by popping it out and ensuring the grooved opening faces the filter. Sometimes there will be an arrow pointing in the opposite direction; this should point toward the engine, i.e. the direction of airflow. Mine was installed before I purchased the car and the OBD2 reading showed zero pounds per minute. I thought I had a huge electrical problem because it "looked right." I switched directions it with the cable facing the opposite direction, correct arrow direction, and immediately the readout on my OBD2 scanner registered appropriately. If your OBD2 scanner doesn't have data readouts on pounds per minute, it may be throwing a MAF code. All the best!

I suspect that many of the supposed MAF sensor failures after K&N installs are actually backwards installation.