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How do I restart or reset my Lennox S40 Smart Thermostat display?

FAQ , Thermostats , Troubleshooting Modified: March 19, 2026

1. In the thermostat, go to Menu > System Settings > Advanced Settings > Restart, and press the restart button.


2. Press the "Yes" button.


To reset the Lennox S40 Smart thermostat please contact your dealer by going to Menu > Lennox Dealer Support Services or Lennox (at 1-800-9-LENNOX)
For more information or a visual representation of steps please reference our user guide here

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