o2 sensor

[capowered240]

Started the car one night just idleing and then all of a sudden I see sparks comin from where the o2 sensor is. Cut the car off, moved the o2 sensor plug. I didn't notice but when I looked at the o2 plug when it had sparked it was on the manifold. So I moved it away from the manifold. Then I looked at it see what it had done and the brown wire was just about melted to the middle wire. The wires were still connected but it had melted the plastic around the wire. So I pulled the 2 wires apart and wrapped them both up with elect tape. After that I went over to were the brown wire is behind the battery and it was almost melted to the wire. It looked like the wire just got really hot and started to melt. Would this have messed up anything. When I unplug and plug the o2 connector it doesn't seem to make any difference the way the car runs. Any suggestions?