hey guys, ive been searching around but i still couldnt find the answer that i want. I noticed there colored blue and white for the primary and secondary o2 sensors. My question is which color is the primary? I saw some pictures shown blue is secondary and white is primary. Im trying to replace my primary o2 sensor, but thanks to the previous owner, he kinda mixed up the o2s. or is there way i can tell front the o2 connectors? ?..please help!!