What does the code E1 mean on a heat controller mini split?

The code E1 on a mini-split heat controller typically indicates a communication error between the indoor and outdoor units. This can occur due to issues such as wiring problems, a faulty control board, or environmental factors affecting the connection. To resolve the issue, it's advisable to check the wiring connections and ensure that the units are properly communicating. If the problem persists, consulting the manufacturer's manual or a professional technician may be necessary.