911GT2

Ok, i was installing the Apex'i turbo timer today (the little silver one) and all was going well. The grey wire was connected to the e-brake, the white wire to the o2 sensor on the ecu, and the black wire to the ground on the ecu. I even did robbinette's alarm modification, cutting the black and yellow wire and attaching the cpu end of it to the white wire. When the car is started, the turbo timer blinks 0.30 and the light next to "time" is lit up. it blinks sporadically, like without any pattern. i can't use the joystick like control on the side of it either
Now here is the tricky part. The check engine light is on. i checked and rechecked the o2 sensor connection, because to the best of my knowledge, that is the only thing we touched that would affect the check engine light. The connection is fine, and according to the apex'i wiring diagram that came with it, it is hooked up to the correct wire in the back of the ecu.
Long story short, i have no clue where to go from here. The car is a 93 touring, 5 spd, with 95k on it. up until now the check engine light has never come on, so it's kinda worryin me. Any help would be greatly appreciated