The thermostat says “E2?”

This is a sensor problem, here are a few fixes:

1. Check to ensure the thermostat is firmly connected to the “C” and “D” ports behind the face plate of the thermostat.
2. If you did not install a floor sensor or it is damaged, set the thermostat to red ambient temperature:
   1. Press the OK button twice to bring up the main menu.
   2. Use the UP or DOWN buttons to scroll to SETTINGS, then press OK.
   3. Use the UP or DOWN buttons to scroll to APPLICATION, then press OK.
   4. Use the UP or DOWN buttons to select ROOM, then press OK.
   5. Set desired temperature (some model of thermostat)
   6. Use the UP or DOWN buttons to scroll to EXIT, then press OK. (do this twice)
   7. Your thermostat will now measure the temperature of the room and NOT the floor sensor. (TIP: You may have to adjust the thermostat temperature higher or lower than expected to achieve desired floor temperature.)
3. Test the floor sensor to measure resistance to check for resistance.
   1. Set your multimeter to the 200k Ohm (Ω) setting.
   2. touch a probe to each end of the sensor wire.
   3. A functioning floor sensor should get a reading between 9,000 and 25,000 ohms, if the sensor fails this test, please see #2 for how to switch to ambient air sensor.

NOTE: Whenever working on ANY wiring for the thermostat, please TURN OFF the breaker powering the thermostat and floor heating system.