Safety first: Switch off power to the thermostat and underfloor heating circuit at the breaker.

Steps to troubleshoot:

Remove the thermostat from the wall plate to access the wiring terminals.
Identify the floor sensor terminals (often labeled "S1/S2" or "NTC").
Check that the floor sensor wires are firmly clamped in the terminals and not broken or corroded.
Disconnect the floor sensor wires and measure resistance with a multimeter. Compare to the Tuya floor sensor spec (commonly 10kΩ at 25°C). Infinite or near-zero resistance indicates a failed sensor.
If resistance is correct at the thermostat end, the sensor is likely good and the thermostat electronics may be faulty.
If the sensor is faulty, replace the floor sensor probe. If it is embedded in the floor, run a new sensor in the spare conduit (if available) and connect it to the thermostat.
Reconnect the sensor, remount the thermostat, restore power, and confirm the E2 code is cleared and floor temperature is displayed.

Note: Never power the floor sensor wires; they are low-voltage sensing lines only.

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

Possible Causes