E72 error on thermostat

[Billy_Khalili]

Seemingly out of nowhere my thermostat started showing an E72 error. I just had my furnace tech in and he did a full system check and everything is working fine outside of the thermostat. I can start the heating system by jumping the wires I have in the W1 and Rh terminals. 

[Jenelyn_O]

Hi Billy_Khalili,

Thanks for reaching out and for being a step ahead of us. You'll see this code if your Nest Thermostat doesn't detect power to a wire, or it can't detect the wires in your thermostat. Based on what you've mentioned, it looks like your wires have the power to provide for the thermostat. I'd like to take a closer look at it. 

Check your thermostat wires:

Important: Protect yourself, your thermostat and your system. Turn off power to your system and thermostat at the breaker or fuse box before exposing or adjusting any wiring.

1. Pull off the thermostat display.
2. Check that the wires are inserted correctly in the thermostat.
   • Check that each wire is fully inserted into its connector and that every connector with a wire is down as shown.
   • Check that each wire has ⅜ inch (6mm) of exposed wire.
   • Check that each wire is connected properly to the system board.
3. Put the display back on the base and turn the power to your system back on.
4. Check if your thermostat is working.

Let me know how it goes.

Best,

Jenelyn