Did you unplug any of the sensors to make more room for yourself to work in there? I installed the Moto Dynamics rear integrated tail light in my Gen 5 and had no problems with CEL light coming on. I only touched the wires needed for the rear tail lamp, it was very tight though, so maybe you unplugged something.. read the code find out what it is and if its nothing to worry about ride it and it should turn off on its own after a few cycles.