Safety: Disconnect power to the thermostat or remove batteries before touching wiring terminals.

Check configuration: In the Eurotronic thermostat menu, verify that the correct sensor mode is selected (e.g., internal, external, or floor sensor). If no external sensor is installed, disable that option to clear E2.
Inspect wiring: If an external/floor sensor is used, open the thermostat and check that the sensor wires are firmly clamped in the designated sensor terminals (often marked S1/S2 or NTC). Tighten any loose screws.
Check cable damage: Follow the sensor cable along the wall or floor entry. Look for cuts, staples through the cable, or crushed insulation. Repair or replace damaged cable.
Test sensor: With the sensor disconnected and power off, measure resistance with a multimeter. Compare to Eurotronic’s NTC curve (approx. 10kΩ at 25°C). Replace the sensor if resistance is far off or unstable.
Replace sensor: Install a new Eurotronic-compatible external/floor sensor, reconnect, and reconfigure the thermostat to use the external sensor.

Thermostat shows E2 and radiator valve does not regulate temperature correctly.

Possible Causes