Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
By permanent code, do you mean you found this code in Mode $0A? If so, the only way to clear it is to drive the vehicle several times to show the on board monitor that the issue is no longer present. No amount of scan tool, resetting or battery disconnecting will clear it.
If you mean that the P0720 is showing up as a Current code and won't clear, I'd say check into the Output Speed Sensor circuit. :lol:
Thank you for the answer, I have a picture of the wiring harness in my repair manual but I can't find it on the van. I have looked at the wiring diagram and PCM connectors and don't find the pins that serve the tranny. I hopw it is not the sensor as you have to take the tranny apart to change it.