DTC C1640: Coding Not Completed: Notes
WARNING: This page is about a different car, the 2009 Mitsubishi Eclipse. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
CAUTION:
Whenever the ECU is replaced, ensure that the CAN bus lines are normal.