it was in fact the wiring harness form the O2 sensor. i disconnected the neg battery cable and the light still came on a few seconds after starting up the engine. i havent put the heat shield back on yet, so could that have anything to do with it?

edit:
i ran the self diagnostic test for the CEL and found it was the oxygen sensor heater (trouble code 41). everything is connected properly, the heat shield was replaced, and i disconnected the neg terminal of the battery for over 5 mins, but the CEL is still coming on. any help?