Display shows 'Er2' and thermostat cannot drive the motorized valve correctly.

Safety: Let the radiator cool before working on the TRV.

• Remove TRV head: Unscrew the Eurotronic TRV head from the valve body and inspect for debris or damage in the drive mechanism.
• Check motor movement: With the head removed and batteries installed, start a calibration or open/close command. Observe if the drive spindle moves. If not, the motor or driver is faulty.
• Inspect gears: If accessible, look for broken or stripped gears. Do not apply grease unless specified by Eurotronic.
• Replace TRV head: If the motor does not move or makes grinding noises, replace the entire TRV head.