Amazon Smart Thermostat
Amazon Smart Thermostat Smart Thermostats Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
Advertisements
E1
Thermostat displays E1 and cannot control heating or cooling
Internal Temperature Sensor Failure
E10
Thermostat shows E10 and indicates an incompatible system.
Incompatible HVAC System Detected
E11
Thermostat displays E11, and the fan runs unexpectedly or not at all.
Fan (G Terminal) Output Fault
E12
Thermostat shows E12, and the heat pump will not heat or cool correctly.
Reversing Valve (O/B) Circuit Fault
E13
Thermostat displays E13, and auxiliary/emergency heat will not engage.
Aux/E Heat Output Fault
E14
Thermostat shows E14, and the screen is very dim or flickers.
Display Power / Backlight Fault
E15
Thermostat displays E15 and becomes very warm to the touch.
Overtemperature Protection / Internal Overheating
E2
Thermostat shows E2 and will not complete setup or control HVAC
Internal Humidity Sensor or Environmental Sensor Fault
E3
Thermostat displays E3 and cannot detect HVAC system correctly
HVAC Equipment Detection Failure
E4
Thermostat shows E4 and will not power on HVAC equipment
C-Wire / Power Supply Fault
E5
Thermostat displays E5 and heating or cooling will not start
Call for Heat/Cool Output Fault
E6
Thermostat shows E6 and cannot connect to Wi-Fi or Alexa app
Wi-Fi / Cloud Connectivity Error
E7
Thermostat displays E7 and shows incorrect date/time or schedules fail
Cloud Sync / Time Synchronization Error
E8
Thermostat shows E8 and HVAC shuts down shortly after starting
Short-Cycle Protection / Overcurrent Detected
E9
Thermostat displays E9 and becomes unresponsive or stuck on logo
Firmware Corruption / Boot Failure
Symptom
The fan runs continuously even when the thermostat is set to Auto and no heating or cooling is requested.
Stuck Fan Relay or G-Circuit Short
Symptom
The room temperature reading on the thermostat is significantly inaccurate compared to a reliable thermometer.
Temperature Sensing / Calibration Error
Symptom
The thermostat buttons or touch interface are unresponsive or laggy.
User Interface Input Failure
Symptom
The thermostat does not follow its schedule or changes temperature on its own.
Scheduling / Smart Feature Misconfiguration
Symptom
The thermostat emits a buzzing or clicking noise during operation.
Relay or Power Circuit Noise
Symptom
The thermostat frequently disconnects from power when touched or bumped.
Poor Mechanical Connection to Wall Plate
Symptom
The thermostat frequently overshoots the set temperature (the room gets too hot or too cold before the system shuts off).
Cycle Rate / Anticipator Configuration Issue
Symptom
The thermostat gets warm, and the wall behind it is discolored or hot.
Overheating Due to Wall Cavity Heat or Electrical Issue
Symptom
The thermostat loses its Wi-Fi connection intermittently, but the HVAC still works.
Intermittent Network Connectivity
Symptom
Thermostat calls for cooling, but the outdoor AC unit does not start.
Open Cooling Call Circuit (Y-Terminal Issue)
Symptom
Thermostat calls for heat, but the furnace does not start (no error on the furnace board).
Open Heat Call Circuit (W Terminal Issue)
Symptom
Thermostat display is very dim but still readable; HVAC works normally
Backlight Degradation or Low Supply Voltage
Symptom
Thermostat has no power, a blank screen, and does not respond at all.
No 24V Power to Thermostat
Symptom
Thermostat is powered but will not connect to the Alexa app during setup.
Initial Pairing / Provisioning Failure
Symptom
Thermostat randomly switches between heating and cooling modes without user input (dual-mode systems)
Auto-Changeover Configuration or Control Conflict
Symptom
Thermostat reboots randomly or frequently restarts during operation.
Unstable Power or Internal Reset Fault
Symptom
Thermostat shows cooling is on, but warm air blows from vents (conventional AC system)
Cooling Call Without Compressor Operation
Symptom
Thermostat shows heat is on, but only cool air blows from vents (with heat pump system)
Heat Pump Mode / Reversing Valve Misconfiguration
Symptom
Thermostat shows heat is on, but the furnace shuts off after a few minutes and restarts repeatedly
Short Cycling Due to Limit or Flame Sensor Issues
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E1 |
Thermostat displays E1 and cannot control heating or cooling
|
Internal Temperature Sensor Failure | View Details |
| E10 |
Thermostat shows E10 and indicates an incompatible system.
|
Incompatible HVAC System Detected | View Details |
| E11 |
Thermostat displays E11, and the fan runs unexpectedly or not at all.
|
Fan (G Terminal) Output Fault | View Details |
| E12 |
Thermostat shows E12, and the heat pump will not heat or cool correctly.
|
Reversing Valve (O/B) Circuit Fault | View Details |
| E13 |
Thermostat displays E13, and auxiliary/emergency heat will not engage.
|
Aux/E Heat Output Fault | View Details |
| E14 |
Thermostat shows E14, and the screen is very dim or flickers.
|
Display Power / Backlight Fault | View Details |
| E15 |
Thermostat displays E15 and becomes very warm to the touch.
|
Overtemperature Protection / Internal Overheating | View Details |
| E2 |
Thermostat shows E2 and will not complete setup or control HVAC
|
Internal Humidity Sensor or Environmental Sensor Fault | View Details |
| E3 |
Thermostat displays E3 and cannot detect HVAC system correctly
|
HVAC Equipment Detection Failure | View Details |
| E4 |
Thermostat shows E4 and will not power on HVAC equipment
|
C-Wire / Power Supply Fault | View Details |
| E5 |
Thermostat displays E5 and heating or cooling will not start
|
Call for Heat/Cool Output Fault | View Details |
| E6 |
Thermostat shows E6 and cannot connect to Wi-Fi or Alexa app
|
Wi-Fi / Cloud Connectivity Error | View Details |
| E7 |
Thermostat displays E7 and shows incorrect date/time or schedules fail
|
Cloud Sync / Time Synchronization Error | View Details |
| E8 |
Thermostat shows E8 and HVAC shuts down shortly after starting
|
Short-Cycle Protection / Overcurrent Detected | View Details |
| E9 |
Thermostat displays E9 and becomes unresponsive or stuck on logo
|
Firmware Corruption / Boot Failure | View Details |
| – |
The fan runs continuously even when the thermostat is set to Auto and no heating or cooling is requested.
|
Stuck Fan Relay or G-Circuit Short | View Details |
| – |
The room temperature reading on the thermostat is significantly inaccurate compared to a reliable thermometer.
|
Temperature Sensing / Calibration Error | View Details |
| – |
The thermostat buttons or touch interface are unresponsive or laggy.
|
User Interface Input Failure | View Details |
| – |
The thermostat does not follow its schedule or changes temperature on its own.
|
Scheduling / Smart Feature Misconfiguration | View Details |
| – |
The thermostat emits a buzzing or clicking noise during operation.
|
Relay or Power Circuit Noise | View Details |
| – |
The thermostat frequently disconnects from power when touched or bumped.
|
Poor Mechanical Connection to Wall Plate | View Details |
| – |
The thermostat frequently overshoots the set temperature (the room gets too hot or too cold before the system shuts off).
|
Cycle Rate / Anticipator Configuration Issue | View Details |
| – |
The thermostat gets warm, and the wall behind it is discolored or hot.
|
Overheating Due to Wall Cavity Heat or Electrical Issue | View Details |
| – |
The thermostat loses its Wi-Fi connection intermittently, but the HVAC still works.
|
Intermittent Network Connectivity | View Details |
| – |
Thermostat calls for cooling, but the outdoor AC unit does not start.
|
Open Cooling Call Circuit (Y-Terminal Issue) | View Details |
| – |
Thermostat calls for heat, but the furnace does not start (no error on the furnace board).
|
Open Heat Call Circuit (W Terminal Issue) | View Details |
| – |
Thermostat display is very dim but still readable; HVAC works normally
|
Backlight Degradation or Low Supply Voltage | View Details |
| – |
Thermostat has no power, a blank screen, and does not respond at all.
|
No 24V Power to Thermostat | View Details |
| – |
Thermostat is powered but will not connect to the Alexa app during setup.
|
Initial Pairing / Provisioning Failure | View Details |
| – |
Thermostat randomly switches between heating and cooling modes without user input (dual-mode systems)
|
Auto-Changeover Configuration or Control Conflict | View Details |
| – |
Thermostat reboots randomly or frequently restarts during operation.
|
Unstable Power or Internal Reset Fault | View Details |
| – |
Thermostat shows cooling is on, but warm air blows from vents (conventional AC system)
|
Cooling Call Without Compressor Operation | View Details |
| – |
Thermostat shows heat is on, but only cool air blows from vents (with heat pump system)
|
Heat Pump Mode / Reversing Valve Misconfiguration | View Details |
| – |
Thermostat shows heat is on, but the furnace shuts off after a few minutes and restarts repeatedly
|
Short Cycling Due to Limit or Flame Sensor Issues | View Details |
No matching codes found
Advertisements