Just installed my Stillen Gen 3 Intakes and after i was finished the "Service Engine Soon" light came on.. What can it be? I put everything back the way it was all sensors and all

 

Run it by autozone and have them pull the code, and write down the code #. You can then reset the code by disconnecting battery for a few minutes. Code probably won't reappear, but always good to ID the code prior to resetting the ECU.

 

Definitely just needs the ecu reset but run the codes anyway.
Every time you disconnect a sensor, especially when it comes to air flow, you'll want to reset so the computer can recognize whatever change you just made.

 

For future reference, disconnect the negative battery terminal whenever you mod anything that involves the electronic system, such as installing CAI, bleeding the brakes, upgrading the headlights, cleaning the throttle bodies, etc. You want the ecu to be under anesthesia (unconscious) when you're doing surgery under the hood.
I didn't have any warning lights after installing the Gen 3 CAI.
You can also pick up a Scan Gauge II while at Auto Zone, it displays and clears codes and much more.
Have fun modding!

 

get an OBDII Bluetooth dongle, and use any number of free apps on your smartphone to read and clear codes. you can also use performance/gauge apps like Torque or Dashcommand with it, too.