TP-Link Kasa
TP-Link Kasa 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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BAT-01
Thermostat shows BAT-01 or low power warning; display may dim or reboot intermittently
Insufficient Power / Battery Backup Low (if equipped)
CFG-01
Thermostat shows configuration error CFG-01 after installation; system runs in wrong mode or not at all
System Type / Wiring Configuration Mismatch
CFG-02
Thermostat displays CFG-02 and will not allow heating or cooling until configuration is completed
Incomplete Initial Setup / Profile Not Saved
E0
Thermostat displays E0 and will not control heating or cooling
Internal Sensor Calibration Error
E1
Thermostat shows E1 and HVAC system does not respond to temperature changes
Room Temperature Sensor Failure
E2
E2 error on display, thermostat cannot control HVAC, may show incorrect room temperature
Remote / External Temperature Sensor Error
E3
Thermostat displays E3 and system will not start heating or cooling
HVAC Equipment Communication / Control Output Error
E4
E4 error appears when calling for cooling; outdoor unit does not start
Compressor / Outdoor Unit Control Fault (Y Circuit Error)
E5
E5 error when calling for heat; furnace or heat pump does not start
Heating Call Output Fault (W Circuit Error)
E6
E6 error appears and thermostat cannot connect to Wi‑Fi or Kasa app
Wi‑Fi Module Communication Error
E7
E7 error and thermostat shows no power from HVAC system, may be running only on internal backup power if available
C-Wire / Power Supply Fault
E8
E8 error appears when using heat pump mode; auxiliary heat may not engage correctly
Heat Pump Reversing Valve / O-B Terminal Error
E9
E9 error and thermostat shows abnormally high or low humidity readings, may disable humidity-based features
Internal Humidity Sensor Failure
SCHED-01
Thermostat ignores schedule or shows SCHED-01 scheduling error in app
Scheduling Configuration Conflict
WiFi-01
Thermostat cannot join Wi‑Fi network; Kasa app shows WiFi-01 or similar connection failure
Wi‑Fi Authentication / SSID Error
WiFi-02
Thermostat frequently disconnects from Wi‑Fi; Kasa app shows offline status and WiFi-02 error
Unstable Wi‑Fi Link / Signal Degradation
Symptom
Thermostat becomes very warm to the touch
Excessive Internal Heat Generation
Symptom
Thermostat buttons or touchscreen are unresponsive
User Interface Input Failure
Symptom
Thermostat calls for cooling but AC does not start
No Cooling Call Output or Open Y Circuit
Symptom
Thermostat calls for heat but furnace does not start
No Heat Call Output or Open W Circuit
Symptom
Thermostat cannot be discovered or added in Kasa app during setup
Pairing Mode / AP Mode Failure
Symptom
Thermostat causes AC to run but indoor blower does not start
Fan Control Misconfiguration with Cooling Call
Symptom
Thermostat causes furnace to run fan only with no heat when calling for heat
Miswired Heat Call or Incorrect System Type
Symptom
Thermostat display is completely blank and unresponsive
No Power to Thermostat
Symptom
Thermostat display is very dim or hard to read
Backlight / LCD Brightness Issue
Symptom
Thermostat does not follow programmed schedule; stays at one temperature
Permanent Hold or Schedule Disabled
Symptom
Thermostat emits buzzing or clicking noises frequently
Relay Chatter or Electrical Noise
Symptom
Thermostat fails to control auxiliary or emergency heat on a heat pump system
Aux/E Heat Output or Configuration Error
Symptom
Thermostat fan setting does not work as expected (fan won’t turn on in ON mode or runs constantly in AUTO)
Fan Control (G Circuit) Misconfiguration or Wiring Fault
Symptom
Thermostat intermittently loses connection to Kasa app when HVAC equipment starts
Electrical Noise or Voltage Sag Affecting Wi‑Fi Module
Symptom
Thermostat loses time or date, causing schedule to run at wrong times
Real-Time Clock / Cloud Sync Issue
Symptom
Thermostat overshoots set temperature, room gets too hot or too cold before system shuts off
Incorrect Cycle Rate / Differential Settings or Sensor Placement Issue
Symptom
Thermostat powers on but frequently reboots or flickers
Unstable Low-Voltage Power Supply
Symptom
Thermostat randomly switches between Heat and Cool modes without user input
Auto-Changeover Configuration or Control Logic Fault
Symptom
Thermostat short cycles the HVAC system (frequent on/off every few minutes)
Short Cycling Due to Control Settings or Sensor Issues
Symptom
Thermostat shows connected in app but does not respond to remote commands
Cloud Connectivity / Command Relay Issue
Symptom
Thermostat shows heating or cooling is on, but room temperature does not change
HVAC Equipment Not Responding to Thermostat Calls
Symptom
Thermostat shows incorrect room temperature compared to other thermometers
Temperature Sensing / Calibration Error
Symptom
Thermostat shows very high or low humidity compared to other hygrometers
Humidity Sensing Error
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| BAT-01 |
Thermostat shows BAT-01 or low power warning; display may dim or reboot intermittently
|
Insufficient Power / Battery Backup Low (if equipped) | View Details |
| CFG-01 |
Thermostat shows configuration error CFG-01 after installation; system runs in wrong mode or not at all
|
System Type / Wiring Configuration Mismatch | View Details |
| CFG-02 |
Thermostat displays CFG-02 and will not allow heating or cooling until configuration is completed
|
Incomplete Initial Setup / Profile Not Saved | View Details |
| E0 |
Thermostat displays E0 and will not control heating or cooling
|
Internal Sensor Calibration Error | View Details |
| E1 |
Thermostat shows E1 and HVAC system does not respond to temperature changes
|
Room Temperature Sensor Failure | View Details |
| E2 |
E2 error on display, thermostat cannot control HVAC, may show incorrect room temperature
|
Remote / External Temperature Sensor Error | View Details |
| E3 |
Thermostat displays E3 and system will not start heating or cooling
|
HVAC Equipment Communication / Control Output Error | View Details |
| E4 |
E4 error appears when calling for cooling; outdoor unit does not start
|
Compressor / Outdoor Unit Control Fault (Y Circuit Error) | View Details |
| E5 |
E5 error when calling for heat; furnace or heat pump does not start
|
Heating Call Output Fault (W Circuit Error) | View Details |
| E6 |
E6 error appears and thermostat cannot connect to Wi‑Fi or Kasa app
|
Wi‑Fi Module Communication Error | View Details |
| E7 |
E7 error and thermostat shows no power from HVAC system, may be running only on internal backup power if available
|
C-Wire / Power Supply Fault | View Details |
| E8 |
E8 error appears when using heat pump mode; auxiliary heat may not engage correctly
|
Heat Pump Reversing Valve / O-B Terminal Error | View Details |
| E9 |
E9 error and thermostat shows abnormally high or low humidity readings, may disable humidity-based features
|
Internal Humidity Sensor Failure | View Details |
| SCHED-01 |
Thermostat ignores schedule or shows SCHED-01 scheduling error in app
|
Scheduling Configuration Conflict | View Details |
| WiFi-01 |
Thermostat cannot join Wi‑Fi network; Kasa app shows WiFi-01 or similar connection failure
|
Wi‑Fi Authentication / SSID Error | View Details |
| WiFi-02 |
Thermostat frequently disconnects from Wi‑Fi; Kasa app shows offline status and WiFi-02 error
|
Unstable Wi‑Fi Link / Signal Degradation | View Details |
| – |
Thermostat becomes very warm to the touch
|
Excessive Internal Heat Generation | View Details |
| – |
Thermostat buttons or touchscreen are unresponsive
|
User Interface Input Failure | View Details |
| – |
Thermostat calls for cooling but AC does not start
|
No Cooling Call Output or Open Y Circuit | View Details |
| – |
Thermostat calls for heat but furnace does not start
|
No Heat Call Output or Open W Circuit | View Details |
| – |
Thermostat cannot be discovered or added in Kasa app during setup
|
Pairing Mode / AP Mode Failure | View Details |
| – |
Thermostat causes AC to run but indoor blower does not start
|
Fan Control Misconfiguration with Cooling Call | View Details |
| – |
Thermostat causes furnace to run fan only with no heat when calling for heat
|
Miswired Heat Call or Incorrect System Type | View Details |
| – |
Thermostat display is completely blank and unresponsive
|
No Power to Thermostat | View Details |
| – |
Thermostat display is very dim or hard to read
|
Backlight / LCD Brightness Issue | View Details |
| – |
Thermostat does not follow programmed schedule; stays at one temperature
|
Permanent Hold or Schedule Disabled | View Details |
| – |
Thermostat emits buzzing or clicking noises frequently
|
Relay Chatter or Electrical Noise | View Details |
| – |
Thermostat fails to control auxiliary or emergency heat on a heat pump system
|
Aux/E Heat Output or Configuration Error | View Details |
| – |
Thermostat fan setting does not work as expected (fan won’t turn on in ON mode or runs constantly in AUTO)
|
Fan Control (G Circuit) Misconfiguration or Wiring Fault | View Details |
| – |
Thermostat intermittently loses connection to Kasa app when HVAC equipment starts
|
Electrical Noise or Voltage Sag Affecting Wi‑Fi Module | View Details |
| – |
Thermostat loses time or date, causing schedule to run at wrong times
|
Real-Time Clock / Cloud Sync Issue | View Details |
| – |
Thermostat overshoots set temperature, room gets too hot or too cold before system shuts off
|
Incorrect Cycle Rate / Differential Settings or Sensor Placement Issue | View Details |
| – |
Thermostat powers on but frequently reboots or flickers
|
Unstable Low-Voltage Power Supply | View Details |
| – |
Thermostat randomly switches between Heat and Cool modes without user input
|
Auto-Changeover Configuration or Control Logic Fault | View Details |
| – |
Thermostat short cycles the HVAC system (frequent on/off every few minutes)
|
Short Cycling Due to Control Settings or Sensor Issues | View Details |
| – |
Thermostat shows connected in app but does not respond to remote commands
|
Cloud Connectivity / Command Relay Issue | View Details |
| – |
Thermostat shows heating or cooling is on, but room temperature does not change
|
HVAC Equipment Not Responding to Thermostat Calls | View Details |
| – |
Thermostat shows incorrect room temperature compared to other thermometers
|
Temperature Sensing / Calibration Error | View Details |
| – |
Thermostat shows very high or low humidity compared to other hygrometers
|
Humidity Sensing Error | View Details |
No matching codes found
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