MIL light is on my 05 v6 dakota. It threw a code p031. I replaced the o2 sensor . I used my code reader to remove the code. The light on the dash stayed lit. i have re read for codes and it says no stored or pending codes. it says MIL light is off, but its not it is on. i disconnected the battery for a while and the light stayed on and rings one when I start the truck up. I dont know how to make it shut off, any ideas/

 

I would suggest that you try another code reader, maybe there is a communication issue or another issue with yours.