Troubleshoot a Nest thermostat overcurrent or E help code

This article applies to the following Google Nest thermostat models in the US and Canada:
Nest Thermostat E	Nest Learning Thermostat
How to tell which thermostat you have

 

Overcurrent help codes that begin with the letter E are typically caused by miswiring the thermostat during installation, or a worn part on the system’s control board which requires service by a professional.