Nest Thermostat Error Code E73: How to Fix It

Q: What does Nest thermostat error E73 mean?

Error E73 indicates no power is reaching the Rh wire, which supplies 24V power for heating operations. This prevents your heating system from functioning properly.

Q: Can I fix Nest E73 error myself?

You can check wire connections and basic wiring issues yourself, but transformer replacement or complex electrical repairs should be done by an HVAC professional for safety reasons.

Q: Why does my Nest thermostat keep showing E73?

Recurring E73 errors typically indicate a failing transformer, loose wire connections, damaged thermostat wiring, or issues with the HVAC control board that need professional diagnosis.

Q: How much does it cost to fix Nest E73 error?

DIY wire connection fixes cost nothing. Professional transformer replacement typically costs $150-300, while control board issues can range from $200-500 depending on the specific problem.

Q: Will E73 error prevent my heating from working?

Yes, E73 error will prevent your heating system from operating because the thermostat cannot send heating calls without power to the Rh wire. Your cooling may still work if it uses a separate power source.

Abstract

Nest thermostat error code E73 indicates there's no power reaching the Rh wire, which supplies power for heating operations. This high-severity error means your heating system won't function properly until the power supply issue is resolved.