E12
Meross Non-Volatile Memory (NVM) Write Error

Thermostat shows E12 and schedules or settings are lost after power interruptions.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Failed EEPROM or flash memory cell on main PCB, Frequent power cycling causing incomplete writes, Firmware bug affecting configuration storage

How to Fix / Troubleshooting

Safety: Turn off power before opening the device; otherwise, this is primarily a functional issue.

Steps:

  • Firmware update: Use the Meross app to check for and install the latest firmware, which may fix NVM handling bugs.
  • Avoid rapid power cycling: Do not repeatedly switch the breaker on and off; allow at least 30 seconds between cycles to avoid corrupting memory writes.
  • Factory reset: Perform a full reset and reconfigure the thermostat. Observe whether settings now persist across power cycles.

Resolution: If E12 continues and settings are not retained, the internal memory chip is failing. The main PCB or thermostat must be replaced.

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Repair Difficulty

Hard 4/5

Required Part

Onboard EEPROM / Flash Memory Chip
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