Sensi
Sensi Smart Thermostats Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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App Cannot Find Thermostat
Sensi app cannot discover or connect to the thermostat during setup.
Pairing / Provisioning Failure
Blank Screen
Sensi thermostat screen is completely blank and unresponsive.
Loss of 24 V Control Power
E1
Thermostat displays E1 and will not control heating or cooling.
Indoor Temperature Sensor Fault
E2
Thermostat displays E2 and shows no or an incorrect temperature reading.
Outdoor Temperature Sensor / Remote Sensor Fault (models that support an external sensor)
E3
Thermostat displays E3 and the system will not run correctly in heat or cool mode.
System Configuration / Equipment Type Error
E4
Thermostat displays E4 and will not complete Wi‑Fi setup.
Wi‑Fi Radio or Network Configuration Error
E5
Thermostat displays E5, and the screen may be dim or unresponsive.
Low Voltage / Power Supply Error
E6
Thermostat displays E6 and cannot control the HVAC system.
Communication Error with HVAC Control Circuit
E7
Thermostat displays E7 and will not operate correctly in heat pump mode.
Reversing Valve / O-B Circuit Error
E8
Thermostat displays E8 and ignores temperature setpoint changes.
Internal Calibration / Sensor Range Error
E9
Thermostat displays E9 and may reboot repeatedly.
Internal Memory / Firmware Error
Flashing Cool Icon
Cool icon flashes, but the outdoor AC unit does not start.
Call for Cooling Not Reaching Condenser
Flashing Heat Icon
Heat icon flashes, but the furnace does not start.
Call for Heat Not Reaching Furnace
Schedule Not Running
Sensi thermostat ignores the programmed schedule and holds a single temperature.
Software Scheduling / Hold Mode Misconfiguration
Wi‑Fi Icon Flashing
Wi-Fi icon on Sensi thermostat flashes continuously, and the app shows the thermostat offline.
Network Connectivity Loss
Symptom
Thermostat backlight flickers, or display brightness changes unexpectedly.
Display Power Regulation Issue
Symptom
Thermostat beeps or chimes unexpectedly (on models with audible alerts).
Alert or Notification Behavior
Symptom
Thermostat calls for cooling, but the room temperature never reaches the setpoint.
Ineffective Cooling Control or Misconfigured System Type
Symptom
Thermostat calls for heat, but the furnace short cycles (turns on and off frequently).
Short Cycling Due to Thermostat Placement or Settings
Symptom
Thermostat clicks, but HVAC equipment does not start.
Relay Operation Without Load Activation
Symptom
Thermostat display fogs or shows condensation inside the lens.
Moisture Intrusion into Thermostat Housing
Symptom
Thermostat displays "Aux Heat" frequently on a heat pump system.
Excessive Auxiliary Heat Usage
Symptom
Thermostat does not power up unless batteries are installed (on battery-assist models).
Insufficient C Wire Power / Battery Assist Dependency
Symptom
Thermostat does not respond to touch or button presses intermittently.
User Interface / Capacitive Touch Failure
Symptom
Thermostat fan setting on AUTO, but blower runs continuously.
Continuous Fan Operation Not Commanded by Thermostat
Symptom
Thermostat frequently disconnects from Wi-Fi but then reconnects.
Intermittent Wireless Connectivity
Symptom
Thermostat loses date/time or settings after a power outage.
Non-Volatile Memory / Backup Power Issue
Symptom
Thermostat mounting plate is loose or the thermostat tilts on the wall.
Mechanical Mounting Instability
Symptom
Thermostat plastic housing feels unusually warm to the touch.
Internal Component Overheating
Symptom
Thermostat randomly reboots or restarts during normal operation.
Intermittent Power or Internal Reset Condition
Symptom
Thermostat shows "Cooling" but only the indoor blower runs; the outdoor unit stays off.
Outdoor Unit Not Energized by Thermostat Call
Symptom
Thermostat shows "Heat On," but heat pump runs in cooling mode (blowing cold air).
Reversing Valve Misconfiguration
Symptom
Thermostat shows "Heating" but only the blower runs; no warm air is produced.
Heat Call Without Burner or Heat Source Activation
Symptom
Thermostat shows a much higher or lower room temperature than actual.
Temperature Sensing / Calibration Error
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| App Cannot Find Thermostat |
Sensi app cannot discover or connect to the thermostat during setup.
|
Pairing / Provisioning Failure | View Details |
| Blank Screen |
Sensi thermostat screen is completely blank and unresponsive.
|
Loss of 24 V Control Power | View Details |
| E1 |
Thermostat displays E1 and will not control heating or cooling.
|
Indoor Temperature Sensor Fault | View Details |
| E2 |
Thermostat displays E2 and shows no or an incorrect temperature reading.
|
Outdoor Temperature Sensor / Remote Sensor Fault (models that support an external sensor) | View Details |
| E3 |
Thermostat displays E3 and the system will not run correctly in heat or cool mode.
|
System Configuration / Equipment Type Error | View Details |
| E4 |
Thermostat displays E4 and will not complete Wi‑Fi setup.
|
Wi‑Fi Radio or Network Configuration Error | View Details |
| E5 |
Thermostat displays E5, and the screen may be dim or unresponsive.
|
Low Voltage / Power Supply Error | View Details |
| E6 |
Thermostat displays E6 and cannot control the HVAC system.
|
Communication Error with HVAC Control Circuit | View Details |
| E7 |
Thermostat displays E7 and will not operate correctly in heat pump mode.
|
Reversing Valve / O-B Circuit Error | View Details |
| E8 |
Thermostat displays E8 and ignores temperature setpoint changes.
|
Internal Calibration / Sensor Range Error | View Details |
| E9 |
Thermostat displays E9 and may reboot repeatedly.
|
Internal Memory / Firmware Error | View Details |
| Flashing Cool Icon |
Cool icon flashes, but the outdoor AC unit does not start.
|
Call for Cooling Not Reaching Condenser | View Details |
| Flashing Heat Icon |
Heat icon flashes, but the furnace does not start.
|
Call for Heat Not Reaching Furnace | View Details |
| Schedule Not Running |
Sensi thermostat ignores the programmed schedule and holds a single temperature.
|
Software Scheduling / Hold Mode Misconfiguration | View Details |
| Wi‑Fi Icon Flashing |
Wi-Fi icon on Sensi thermostat flashes continuously, and the app shows the thermostat offline.
|
Network Connectivity Loss | View Details |
| – |
Thermostat backlight flickers, or display brightness changes unexpectedly.
|
Display Power Regulation Issue | View Details |
| – |
Thermostat beeps or chimes unexpectedly (on models with audible alerts).
|
Alert or Notification Behavior | View Details |
| – |
Thermostat calls for cooling, but the room temperature never reaches the setpoint.
|
Ineffective Cooling Control or Misconfigured System Type | View Details |
| – |
Thermostat calls for heat, but the furnace short cycles (turns on and off frequently).
|
Short Cycling Due to Thermostat Placement or Settings | View Details |
| – |
Thermostat clicks, but HVAC equipment does not start.
|
Relay Operation Without Load Activation | View Details |
| – |
Thermostat display fogs or shows condensation inside the lens.
|
Moisture Intrusion into Thermostat Housing | View Details |
| – |
Thermostat displays "Aux Heat" frequently on a heat pump system.
|
Excessive Auxiliary Heat Usage | View Details |
| – |
Thermostat does not power up unless batteries are installed (on battery-assist models).
|
Insufficient C Wire Power / Battery Assist Dependency | View Details |
| – |
Thermostat does not respond to touch or button presses intermittently.
|
User Interface / Capacitive Touch Failure | View Details |
| – |
Thermostat fan setting on AUTO, but blower runs continuously.
|
Continuous Fan Operation Not Commanded by Thermostat | View Details |
| – |
Thermostat frequently disconnects from Wi-Fi but then reconnects.
|
Intermittent Wireless Connectivity | View Details |
| – |
Thermostat loses date/time or settings after a power outage.
|
Non-Volatile Memory / Backup Power Issue | View Details |
| – |
Thermostat mounting plate is loose or the thermostat tilts on the wall.
|
Mechanical Mounting Instability | View Details |
| – |
Thermostat plastic housing feels unusually warm to the touch.
|
Internal Component Overheating | View Details |
| – |
Thermostat randomly reboots or restarts during normal operation.
|
Intermittent Power or Internal Reset Condition | View Details |
| – |
Thermostat shows "Cooling" but only the indoor blower runs; the outdoor unit stays off.
|
Outdoor Unit Not Energized by Thermostat Call | View Details |
| – |
Thermostat shows "Heat On," but heat pump runs in cooling mode (blowing cold air).
|
Reversing Valve Misconfiguration | View Details |
| – |
Thermostat shows "Heating" but only the blower runs; no warm air is produced.
|
Heat Call Without Burner or Heat Source Activation | View Details |
| – |
Thermostat shows a much higher or lower room temperature than actual.
|
Temperature Sensing / Calibration Error | View Details |
No matching codes found
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