It is not the sensor itself I tried one I know is good an hour or two ago and it was the same. I never got a check engine light until I unplugged the o2 sensor I didnt think the computer had picked anything up. How do you check for codes with this obd 1 set up? I know each manufacturer is different. I have pulled each spark plug and looked at each of them. They all look the same, a little white like running hot maybe. I dont know what else to check maybe fuel pressure? Ill be doing that tomorrow.