Okai error codes

[Lothean]

Diagnostic Codes
01E ~ High current protect
02E ~ Low voltage protect (battery or cHigh current protect)
03E ~ High voltage protect (controller problem)
04E ~ Locked motor protect
05E ~ Controller problem (MOS burned)
06E ~ Controller problem
07E ~ Motor problem
08E ~ Motor OT
09E ~ Throttle problem
10E ~ Brake problem (Usually broken brake lever)
11E ~ Signal transmission problem (controller problem)
12E ~ Signal transmission problem (controller problem)
13E ~ Cannot communicate with BMS

[Chubbs]

How would you go about fixing a 12e error code?