Thermostat Reads Error Message “ER2” on the Display?
The Thermostat Reads ER2
When the thermostat reads “ER2,” the floor sensor has a short circuit or has a loose connection. Your electrician must secure connections and test the probe using a multimeter set to the lowest possible ohms scale. The resistance reading should be between 7 and 17 ohms. If a short is found and a backup sensor probe was not installed, you can bypass the error message by setting the thermostat to read the air temperature instead.
Menu > Settings > Set Heating Target > Target Air Temperature