All I can find is information for under voltage. I know it's not the same
problem but it might be a starting point
00446 - Function Limitation due to Under-Voltage
00446 - Function Limitation due to Under-Voltage: Lower Limit Exceeded
Possible Symptoms
Malfunction Indicator Light (MIL) ON
Possible Causes
Fuse(s) faulty
Supply Voltage low
Battery faulty
Generater faulty
Possible Solutions
Check Fuse(s)
Check Supply Voltage
Check/Replace Battery
Check/Replace Generator