I've been waiting for this to happen. (CEL)
 

I recently installed a K&N intake, and not even a tank of gas later my check engine light comes on.

I know we've all talked about K&N kits and their effect on mass air sensors, so thats why I've almost been expecting it.
I don't know if its the MAS for sure, but I want to get it checked out asap.

Although it just happened tonight, the car still runs like a top.

Are there any tell-tale signs when the MAS goes out?

This is the symptom when the MAF is bad. This problem happened to one of the member.

No Torq from Mid-Hi RPMs when cold, No torq in Hi rpm's warm


Ok after receiving my from the bodyshop, I immediatly noticed that the acceleration was lacking BIG TIME. So i figure since it wasnt drivin in 1 month I filled the tank up with gas and drove it abit and that seemed to clear up the low-mid RPM lack in power... However, the High RPMs (5k & Up) power curve seems to flat line.

Usually when that happens, I clean the MAF and problem solved but this time it didnt work, I also cleaned the airfilter and no change.

Yesterday morning I did notice that when the engine is cold, the mid-high rpm acceleration is non-existant until the engine warms up for about 30 seconds later, then the mid RPM power is there again... but still no power past 5k RPM's.

I do have K&N intake for 18 months. No issue, no problem. Check your MAF position and connector. The hollow mouth should facing the incoming air from the air filter.

I'm a couple hundred miles into the K&N with no problem. Pull the code and see what you find...

Do you know where they plug into (location) on the 996 to pull the codes?

I took another car up to AutoZone and they were able to easily diagnose. Thinking about doing the same with the Pcar, but I seriously doubt they will know where to plug in on a 996. I don't know where it is either, as I just bought the car.

Joe,

It located at your left knee height. Right above the interior fuse box.

If you are sitting in your car....the plug will be right above your left knee. Rectangular shaped. I think it's purple in color. My guess is the MAF.. I had the same problem when I installed my K&N.
Good luck

Update
 

I disconnected the battery and cleaned the MAF sensor. The sensor appeared to be clean with no oil on it at all.

I fired the car up and the CEL was no longer lit up. So I took it out for a spin and really ran the revs up to 4 and 5K to see if I could get the CEL to come back on. The car still runs like a top.

Do you think this corrected the issue, or do I still need a new sensor?

Thanks,

Joe

Only time will tell...

I'm installing the K&N Sunday and these posts bother me...a lot. Is it worth the trouble?

Other than the crap directions making you want to throw the whole thing away, it is worth it. Just be sure you've disconnected your battery BEFORE doing the install.

Did u disconnect the battery and let the ECU reset to recognize the new air when u originally installed the intake? If not the MAF went nuts because of all the new air it was getting. This was the issue they told me when I called them.

Yes. I learned to do that from reading the posts on this forum.

After I disconnected the battery and checked the MAF for dirt the CEL has not come back on. I'm going to run the car hard again tomorrow and see what happens.

My MAF went bad from the filter after a while. I disconnected the MAF harness and the car ran good. Thats how I knew the MAF was bad. Later I cleaned the MAF with WD40 and dried it with the air gun. That fixed it.