Quick lookup for error codes and common symptoms on Mysa for Baseboards.

Last updated: July 19, 2026

Error codes that may appear on your Mysa for Baseboards display indicate hardware issues that need attention.

H2 — No Heater Detected

Applies to: V2 and V1 only (Lite does not display H2)

What it means: Mysa did not detect a heater between the Load and L2/N connections.

Possible causes:

  • Loose wire connection in a wire nut — as more wires go into a wire nut, connections can come loose

  • Heater load wire not connected to Mysa Load

  • Heater has malfunctioned

  • Wiring error during installation

What to do:

  1. Turn off power at the circuit breaker

  2. Remove the thermostat faceplate

  3. Check that all wires are properly secured in each wire nut — give each wire a gentle tug

  4. Make sure heater wires connect between Mysa Load and L2/N

  5. Reattach the faceplate and restore power

If the error clears, your thermostat is working correctly. If it persists, contact support.

H4 — Relay Damaged

Applies to: V2 and Lite only

What it means: The internal relay was damaged, usually from a wiring error or exceeding the maximum load. This can appear days, weeks, or even months after installation.

What to do:

This error cannot be cleared — it indicates a hardware failure that requires thermostat replacement. Contact support immediately.

Warning: Do not continue using a thermostat displaying H4. Turn off power at the breaker and contact support.

Other Error Codes

Other error codes indicate hardware defects that cannot be fixed by the user. If you see a code not listed above, contact support with a photo of the error.

Not an Error Code? You Might Be Looking For:

If your thermostat is showing a blank display, won't connect, or isn't heating — but isn't showing a specific code — these aren't error codes and are covered elsewhere:

  • Baseboard: Won't Power On / No Display

  • Baseboard: Heat Won't Shut Off / No Heat

  • Pairing & Wi-Fi Troubleshooting

Get Support

Include with your message:

  • A photo of your thermostat display (showing any error code)

  • A description of what's happening

  • Your thermostat model (V2, Lite, or V1) — found in app under Settings > Thermostat Info

Email: install@getmysa.com (installation/wiring) or support@getmysa.com (general)