Gen3: Error codes

Last updated: October 5, 2026

On Gen3, error codes have different meanings than on V1, V2, or Lite. Do not use the older H2 / H4 explanations for this product.

Gen3 can show H1, H2, H4, and H5. H5 is unique to Gen3 (V1/V2/Lite help does not list it). This is line-voltage equipment. If you need to inspect wiring, turn the breaker off first and confirm power is off. Do not work live.

H1: Over-temperature

The thermostat detected a temperature that is too high.

What to do:

  1. Turn the breaker off.

  2. Make sure the heater is not blocked and the thermostat is not sitting on another heat source.

  3. Restore power only after the area has cooled.

  4. If H1 returns, leave the breaker off and contact Mysa Support.

H2: Under-current

The thermostat measured less current than expected while it was trying to deliver heat. On Gen3 this means under-current. It is not the V1/V2 “no heater detected” H2.

What to do:

  1. Turn the breaker off before any wiring check.

  2. Confirm the heater load is connected and the circuit is the one you think it is.

  3. If you are not an electrician, leave the breaker off and contact support or a licensed electrician.

  4. If H2 continues after a correct, powered installation, contact Mysa Support.

H4: Current while output should be off

The thermostat measured current through the heater when output should have been off. On Gen3 this is not the V2/Lite “relay damaged” H4.

What to do:

  1. Turn the breaker off. Do not keep using the thermostat while H4 is showing.

  2. Do not try to clear this by cycling the app alone.

  3. Contact Mysa Support. Tell them this is Gen3 (BB-Gen3-0), not V2.

H5: Over-current

H5 means over-current. It can appear when measured current reaches approximately 18 A. Gen3 remains rated for a maximum of 16.7 A. The display shows H5.

This is not the V1/V2 relay H5/H6 check (stuck open or stuck closed). Gen3 uses a triac. There is no H6 on Gen3.

The circuit breaker rating alone does not confirm heater compatibility. Keep the combined heater load within 4,000 W at 240 V or 2,000 W at 120 V.

What to do:

  1. Turn the breaker off.

  2. Add up every heater on that circuit. If the total is above 4000 W at 240 V or 2000 W at 120 V, reduce the load before restoring power.

  3. Do not restore power until the load is confirmed safe.

  4. Contact Mysa Support or a licensed electrician. Tell them this is Gen3 (BB-Gen3-0) and you saw H5.

What these codes are not

  • V1/V2/Lite H2 (“no heater detected”) does not apply here.

  • V2/Lite H4 (“relay damaged, cannot be cleared”) does not apply here. Gen3 uses a triac, not that relay design.

  • V1/V2 H5 and H6 (relay stuck-open / stuck-closed) do not apply here. On Gen3, H5 is over-current only, and there is no H6.

  • A blank display, a pairing problem, or no heat without a code is not an H-code. Use the pairing or power articles for those.

When you contact support

Include:

  • A photo of the display showing the code

  • Model: Gen3 / BB-Gen3-0 / MYSA BB V3-0

  • Voltage (120 V or 240 V) and heater wattage if you have it

  • What the heater was doing when the code appeared

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