Error codes on Mysa for Electric Baseboard Heaters

Last updated: October 27, 2026

Do you have Gen3? This article is for V2, Lite and V1. For the Gen3 error codes, see Gen3: Error codes.

An error code on the Mysa display tells you that Mysa found a problem. Find the code that you see, then do the steps.

Warning: Installing this product involves handling high voltage wiring. To avoid personal injury, or death, turn off your circuit breakers and follow the proper safety precautions before proceeding.

H2 error code (V2 and V1)

Mysa did not detect a heater between Load and L2/N. Lite does not display H2.

A very small heater can cause an H2 error on the Mysa display.

  1. Turn off the circuit breaker.
  2. Make sure that the Mysa Load lead connects to the heater wire. The colour of the heater wire is not important.
  3. Make sure that each wire is tight in its wire nut. When a wire nut holds more wires, the wires can become loose.
  4. Turn on the circuit breaker. Make sure that the error code goes away.

If the error code does not go away, contact support.

H4 error code (V2)

Mysa detected current to the heater when the heater must be off.

  1. Turn off the circuit breaker.
  2. Do not use Mysa again until you speak with support.
  3. Contact support. Send a photo of the display.

Other error codes

If you see a different code, contact support. Send a photo of the display.

No error code?

If the display is dark, or Mysa does not connect or does not heat, see these articles:

Get support

Send this information:

  • A photo of the display with the error code.
  • What you see.
  • Your Mysa model. In the Mysa app, select your Mysa. Then go to the Settings tab > Thermostat Info.