With out knowing what brand of scanner you have , this question is not answerable.
You reset it with an OBD2 scan tool after it is repaired.
You reset it with an OBD2 scan tool.
What engine light. If you are referring to the Check Engine light then reset it with an OBD2 scan tool after the problem is repaired.
With an OBD2 scan tool.
I think you are assuming that to reset the check engine light you can just disconnect the battery. Disconnecting the battery on a 2004 OBD2 compliant vehicle will not reset the check engine light. It must be reset with an OBD2 scan tool. This would work on OBD1 vehicle but not on OBD2 vehicles. So the radio issue is mute. Have the problem that set the check engine light repaired and then reset the light with the tool. Reset the light without correcting the problem and the light will just come back on.
After the repair, you reset it with an OBD2 scan tool.
With an OBD2 code reader
Repair the problem then use an OBD2 scan tool to reset the light.
Reset with an OBD2 scan tool, after the repair of whatever triggered the light.
Repair the problem and then reset it with an OBD2 scan tool.
It is reset with a OBD2 scan tool, after the repair of the system.
You can try disconnecting the negative battery cable for about five minutes. If this does not reset the check engine light you will need an OBD2 scan tool to reset it.