Google Nest Thermostat Error Code E73: How to Fix It

Q: What does Nest error code E73 mean?

Error code E73 means your Nest thermostat cannot detect the heating wire connection at the Rh and W terminals. This usually indicates a wiring problem, loose connection, or compatibility issue preventing proper heating system control.

Q: Can I fix Nest E73 error myself?

Yes, you can often fix E73 error yourself by checking and tightening wire connections at the Rh and W terminals. However, if the problem is with your HVAC system's wiring or control board, you may need professional help.

Q: Why does my Nest keep showing E73 error?

A persistent E73 error usually indicates loose wire connections, damaged wiring, or an incompatible heating system. Check that your red (Rh) and white (W) wires are properly connected and that your system is compatible with Nest thermostats.

Q: Do I need special wires for Nest thermostat?

Most Nest thermostats require standard thermostat wire (18-24 AWG) with at least Rh (power) and W (heating) connections. Some systems may need additional wires like C (common) for power or Y (cooling) for air conditioning.

Q: How do I know if my heating system is compatible with Nest?

Check Google's Nest compatibility checker online or look for Rh and W wires at your old thermostat. Most gas furnaces, electric furnaces, and boilers are compatible. Heat pumps and some older systems may need additional wiring or compatibility accessories.

Abstract

Google Nest error code E73 appears when your thermostat cannot detect the heating wire connection at the Rh and W terminals. This typically indicates a wiring issue, loose connection, or compatibility problem that prevents your thermostat from controlling your heating system properly.