My 2003 WRX has no mods yet other than the AEM short ram. As soon as I installed it the Check Engine Light came on. I ran the code through a scanner and it reads bank one lean. Also my idle speed dropped to just under 500 RPM.

Any help at all would be greatly appreciated.

The system is fully secured and tight and the MAF is not on backwards or dirty.

 

well i've driven it extremely babied for about 20 miles thus far and tomorrow will open it up and see if it comes back but so far so good.

Status report: About 10 miles into my drive today at 2500 RPM's that beautiful yellow light shown bright once again. It took longer for it to come on this time than in the past but it's still there.

 

I installed the same intake on my 03 wrx with a borla exhaust and got the same problem. I reset the computer a couple times by dissconecting the battery and it always comes back. Today i had it reset with a code puller. So we will see. Id also like to know of any fixes for this problem.

 

After months of research and trial and error on this one i have no answer for a proper fix. AEM refuses to do anything for me unless i bring the car to them. They inspected my system and it is in fact within spec. No matter what you do to clear that code it will come back after only a short time driving. Thw WRX doesnt take well to many different intake systems because the Mass airflow sensor is sensative. If you wanted to spe3nd the money amyway, a piggy back ECU might fix it. By the way the code is most likely reading bank one lean.
Here what I have neded up with as my solution. I am selling my AEM short ram and replacing it with the stock box and a drop in K&N and removing the resonator box. Simple as that. Only a few WRX's have this problem so most likely if you sell it to someont it will work fine.

 

As we have seen from many other people after market intakes are notorious for causing CEL's. My suggestion is to buy that thingy (technical name) that prevents the CEL light from coming on. Simply resetting the ECU will not do nothing more than waste your time. And thats the gist.

Ryan

 

The question then would have to be is the CEL legit. Is my engine actually running lean. Also if you use any device (or for those who are really cheap black tape) to prevent the CEL from coming on what other potential problems are you preventing yourself from seeing? I'd have to say i dont think thats a good idea.

 

I swapped it back out with the stock box and the problem went away so Ill say its not the Mass Air Sensor.

The AEM is now gone and the K&N is in. Recomendation for those who follow the same path is make sure you dont over oil the filter or you will screw up your Mass Air Flow Sensor.