Here is the page from the L series code manual.
I am not a DTC expert. Sheepfarmer is the one! There are others as well like Whitetiger, Lugbolt...............
If you have a volt meter, I would measure voltage across the battery terminals with the engine running.
The system has seen 16+ volts which is very high. Look for any wires not securely plugged into the alternator which could feed the charging system erroneous signals on the state of the battery charge..
Note on the attached page that there is a "Limp Home Mode," which is how the designers intended the tractor to operate with reduced performance for a short time when this specific error code is thrown.
This is different than say a low oil pressure condition where the engine would be stopped or serious damage would happen immediately.
Another member with a different L series posted a page on resetting the computer. See if it makes any sense when looking at your machine and its various buttons.
The Code page has a line Recovery from Error which in this case is Key switch Off. This could mean once the error is corrected the code will go away just by turning the Key to OFF.
Remember....... I am not a Code expert................
Dave