How to rectify an Er 1 Error on the E91 Joule Thermostat
If your E91 Joule thermostat is showing an Er1 error then this means that the thermostat is looking for the wrong sensor.
To fix this we need to tell the stat to look for its internal air sensor. To do this push the power button on the bottom right hand corner of the Thermostat screen so that the screen displays "OFF"
Push and Hold the Book symbol at the top right of the screen, whilst holding down this icon tap the power button in the bottom right hand corner of the screen and the thermostat will enter its field parameter settings menu and will display "1Adj"
Push the book button once and the screen will show "2SEn" on the lower part of the screen and "OUr" will be displayed at the top.
Push the up arrow until "In" is displayed. Once displayed push the power button once to save the setting, the screen will then show "OFF", push the power button again to turn on the stat and the Er 1 fault should have cleared.