Tuya Smart Thermostats Error Codes

Cloud

Thermostat shows a cloud icon with a slash or 'Cloud' error; local control works but app shows device offline

Cloud Service or MQTT Connectivity Issue

E1

Thermostat displays E1 and cannot control heating; room temperature reading is obviously wrong or shows dashes/--

Internal Room Temperature Sensor Failure

E2

Thermostat shows E2 and cannot read floor temperature in underfloor heating mode

External Floor Sensor Failure

E3

Thermostat displays E3 and heating/cooling output is disabled; internal temperature fluctuates wildly or is stuck

Internal Temperature Sensor Short Circuit or Overrange

E4

Thermostat shows E4 and will not control the load; often appears on electric underfloor heating models

Overheat Protection / High Temperature Alarm

E5

Thermostat displays E5 and does not energize the heating/cooling output; may be accompanied by a hot or buzzing thermostat

Output Relay or Triac Overcurrent / Short Circuit Protection

E6

Thermostat shows E6 and cannot control the HVAC system; often on Tuya Wi-Fi thermostats for boilers or heat pumps

Power Supply or Low-Voltage Input Fault

E7

Thermostat displays E7 and does not respond correctly to setpoint changes; may show extremely low or high temperature values

Calibration Error or Sensor Out-of-Range

E8

Thermostat shows E8 and intermittently shuts down or reboots; may feel unusually warm to the touch

Internal Overtemperature Protection

E9

Thermostat displays E9 and refuses to start heating or cooling; often after a wiring change or power surge

Configuration or Hardware Protection Lockout

Er1

Display shows Er1 and thermostat is unresponsive or stuck in standby

Keypad or Touch Panel Communication Error

Er2

Thermostat shows Er2 and cannot be controlled via buttons or touch; some keys may be stuck

Key Stuck or Button Matrix Fault

Err

Thermostat shows generic 'Err' on the display and does not operate the HVAC system

General System Error / Firmware Fault

Hi

Display shows 'Hi' or maximum temperature and thermostat may shut down or refuse to heat

Temperature Above Measurement Range / Sensor Overflow

Lo

Display shows 'Lo' or very low temperature and thermostat will not heat correctly

Temperature Below Measurement Range / Sensor Underflow

Lock

Display shows a lock icon or 'Lock'; buttons do not respond and settings cannot be changed

Child Lock / Keypad Lock Enabled

OF

Display shows 'OF' or 'OFF' and thermostat does not call for heating or cooling even when room is cold/hot

System Off / Standby Mode Misinterpreted as Fault

WiFi

Thermostat shows a Wi-Fi icon with an exclamation mark or 'WiFi' error and cannot be controlled from the Tuya/Smart Life app

Wi-Fi Connectivity Failure

Symptom

Thermostat buttons or touch screen do not respond, but display is on and Wi-Fi control may still work

Local User Interface Failure

Symptom

Thermostat calls for heat but boiler or furnace does not start; external call indicator on boiler is inactive

Open Control Circuit Between Thermostat and Boiler

Symptom

Thermostat causes breaker to trip when heating turns on, or thermostat itself becomes very hot

Overcurrent or Short in Heating Output Circuit

Symptom

Thermostat display is very dim or unreadable, but device still controls heating

Backlight or LCD/OLED Display Degradation

Symptom

Thermostat does not follow programmed schedule; heating turns on/off at wrong times

Scheduling / Timekeeping Fault

Symptom

Thermostat does not power on at all; display is blank and no LEDs are lit

No Power to Thermostat

Symptom

Thermostat does not respond to voice assistant commands (Alexa/Google), though app control works

Third-Party Integration / Skill Issue

Symptom

Thermostat fails to control cooling (AC) while heating works correctly

Cooling Output Circuit Fault or Misconfiguration

Symptom

Thermostat frequently disconnects from Wi-Fi and appears offline in the Tuya app, then reconnects later

Intermittent Wi-Fi Connectivity

Symptom

Thermostat housing is warm or hot to the touch even when heating is off

Internal Heat Build-Up

Symptom

Thermostat makes loud clicking noises frequently, disturbing occupants

Relay Noise / Excessive Switching

Symptom

Thermostat overshoots set temperature significantly; room becomes too hot before heating turns off

Poor Temperature Control / Overshoot

Symptom

Thermostat powers on but does not call for heat even when room temperature is below setpoint

Heating Call Failure

Symptom

Thermostat randomly resets or reboots, especially when relay switches on/off

Power Supply Instability or Electrical Noise

Symptom

Thermostat short cycles the heating system: boiler turns on and off frequently in short intervals

Short Cycling Due to Control Settings or Sensor Placement

Symptom

Thermostat shows 'heating' icon but electric underfloor heating remains cold

Open Heating Circuit or Failed Output Device

Symptom

Thermostat shows connected in app but commands (changing setpoint/mode) are delayed or not applied

Cloud Command Latency or Local MCU Communication Issue

Symptom

Thermostat shows room temperature much higher or lower than actual by several degrees

Temperature Measurement Inaccuracy

Symptom

Underfloor heating controlled by Tuya thermostat is uneven; some areas too hot, others cold

Improper Floor Sensor Placement or Load Distribution