The heater disable methods noted in links posted by Garsh are not the source of error codes. Those methods fool the HVAC controls so they think the hot water tank is up to temperature and do not turn on the heating elements. I installed a temporary resistor at the water temperature sensor connector near the water tank (which is near the 12-volt battery) and it kept the heating elements off without setting error codes in my 2011. I would have purchased the plug-and-play kit for a neat permanent installation if the car had not been totaled.
Replacing the 12-volt battery has eliminated the communication errors associated with the HVAC system so you are left with the PTC heater element and supply voltage errors. I will try to look at the service manual this weekend, although going from memory of what the circuit looks like, I suspect the heating elements failed and then blew the supply circuit fuses in the DC junction box. If so, you would need a new heater assembly (hot water tank) and either a new DC junction box or new fuses if you can open the junction box and replace the fuses. You should also carefully inspect the high-voltage DC wiring between the junction box and water tank. Be very careful when working with the HVDC circuits. You should also check the 12-volt pump that circulates the hot coolant because lack of coolant flow might cause overheating and failure of the heating elements.