E12
American Standard
Non-Volatile Memory / Data Storage Fault
Thermostat shows E12 and schedules or settings are not saving correctly
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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
Corrupted internal memory, Power loss during write operation, Defective flash memory chip, Firmware bug affecting storage
How to Fix / Troubleshooting
Safety: Turn off power at the breaker before removing the thermostat from the wall.
- Soft reset: Use the thermostat menu to perform a soft reset (without erasing Wi‑Fi). Test if new schedules can be saved.
- Factory reset: If soft reset fails, perform a full factory reset. Reconfigure system type, Wi‑Fi, and schedules from scratch.
- Stable power: Ensure the 24V supply is stable (no frequent brownouts). If your home has power quality issues, consider a whole-home surge protector or consult an electrician.
Resolution: Persistent E12 after factory reset usually indicates a failing memory chip; replace the thermostat.
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Repair Difficulty
Medium
3/5
Required Part
American Standard smart thermostat (internal memory)
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