New to Ford trucks and this forum, just got a nice 96 F150, I got CEL and it is one of the O2 sensors, something about the "heating circuit" in one, stupid me erased the code but I'm sure it will come back soon, although maybe not, the thing runs great. Anyway there are "banks" and sensor numbers. Anyone know which one is which (total of three, two in the manifold and one post cat I believe), are all these the same type sensor. Are the four wire leads power, signal to computer, ground, and what would the other be, signal ground? Are there separate fuses and relays for these sensors, nothing in the fuse panel I can see. I read that many sensors don't use heaters that are near the head because they get hot enough, so i wonder if it detects a heater malfunction but still does its job anyway. Ya, got a lot of questions but I love this truck and like the idea of a big displacement inline six and want to keep it running tip top, thanks