I have a 99 GMC Suburban. My service engine soon light has been on for two weeks now. The day it went on I went to autozone and had the code red. It was the o2 sensor. I replaced the sensor the next morning. I went back to autozone to have them clear the code but they said they were not aloud too. I then went to o'rileys to see if they could reset the code. O'Rileys said they were not aloud to either. The guy at O'Rileys said the code should clear after a little while by it's self. The code still has not cleared. I tried disconnecting the negative cable. I had it disconnected for two hours this evening and just reconnected it. The code is still showing. Any ideas on how I can get the code cleared? Having the service engine soon light on is driving me nuts!