E11
Johnson Controls
Non‑Volatile Memory / Configuration Corruption
E11 displayed and thermostat reports internal memory or configuration error; settings may not save.
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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 EEPROM/flash memory, Interrupted firmware update, Power surge damaging memory cells, Defective main control board
How to Fix / Troubleshooting
Safety: Turn off power to the HVAC system before removing the thermostat.
- Step 1 – Soft reset: Use the thermostat menu to perform a soft reset or reboot if available.
- Step 2 – Factory reset: Perform a full factory reset from the installer menu. Note that this will erase all schedules, Wi‑Fi settings, and custom configurations. Reprogram the thermostat afterward.
- Step 3 – Firmware reflash (if supported): Using the Johnson Controls app or service tool, attempt to reload the latest firmware. Ensure power is stable during the process.
- Step 4 – Surge protection: If the error followed a storm or power event, consider adding surge protection to the HVAC circuit.
- Step 5 – Replace thermostat: If E11 returns after reset and reprogramming, the internal memory device on the main PCB is failing. Replace the thermostat main control board or entire thermostat.
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Repair Difficulty
Medium
3/5
Required Part
Main Control Board (EEPROM/Flash Memory)
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