Heater stopped working due to under-voltage.

Most of the time under-voltage is momentary and after clearing the code through your controller, your heater should be able to resume normal operations. If not, you most likely have issues with your electrical system. 

First check the battery charge. If the battery has lost its charge or degraded over time it can sometimes cause under-voltage. A faulty battery management system can also potentially cause under-voltage issues.

We always recommend using the vehicle's own batteries, as these are less likely to fail. 

Under-voltage can be displayed by one of two codes: 200 or 222. If both codes are present, it can also indicate a problem with the blower motor. In this case, in-depth diagnostics will be required.