ecobee devices will update themselves automatically, provided they are connected to Wi-Fi. When a firmware version is ready for the public, it will be pushed out gradually over a period of time to all applicable ecobee devices.
You can find the firmware version of your ecobee thermostat by going to MAIN MENU > ABOUT, through the thermostat interface.
Auto-Upgrade Firmware Versions as of January 19th, 2020 :
| Device | Firmware Version |
|---|---|
| ecobee SmartThermostat with Voice Control | 4.6.33.128 |
| ecobee4 | 4.6.33.124 |
| ecobee3 lite | 4.6.33.122 |
| ecobee3 | 4.6.33.118 |
| Smart Si | 3.4.1.56 |
| EMS Si | 3.4.1.56 |
| Switch+ | 4.5.81.214 |