the nest learning thermostat isn't learning my schedule, it keeps changing to eco temps when i'm home

Diagnosis

The conflict occurs because the 4th Gen Nest Learning Thermostat is attempting to balance three competing logic systems: Auto-Schedule, Home/Away Assist (Presence Sensing), and the Eco temperature thresholds. When the device switches to Eco temperatures while you are physically present, it is typically a failure of the "Presence Sensing" logic. The thermostat believes the house is vacant because it is relying on outdated geofencing data from your smartphone or it isn't detecting motion via the built-in far-field sensors.

This often happens if the "Home/Away Assist" is configured to prioritize phone location over the internal occupancy sensor. If your phone's location permissions are set to "While using the app" instead of "Always," or if battery optimization is killing the Nest app in the background, the thermostat will assume you've left the premises. Consequently, it overrides any "learned" schedule to trigger the Eco energy-saving setpoints, which are designed to maintain a minimum safe temperature rather than your comfort preference.

How to Fix It

To stop the thermostat from defaulting to Eco mode while you are home, you must synchronize the presence sensing and clear the learned history to start fresh. Follow these exact steps:

1. Reset the Learned Schedule: Press the thermostat ring to open the Quick View menu. Rotate to Settings > Reset > Schedule. Confirm the reset. This wipes the "incorrect" patterns the device has learned, preventing it from fighting your manual inputs.
2. Calibrate Home/Away Assist: Go to the Google Home app on your mobile device. Select your Thermostat > Settings > Presence Sensing. Ensure that "Allow this device to help determine if you're home" is toggled ON for your current phone.
3. Adjust Location Permissions: Open your smartphone's system settings > Apps > Google Home > Permissions > Location. Change the setting to "Allow all the time". If this is set to "While using the app," the thermostat will trigger Eco mode the moment you close the app.
4. Configure Eco Temperature Thresholds: On the thermostat device, rotate to Settings > Eco. Adjust the Heat and Cool setpoints to be closer to your actual desired temperatures (e.g., instead of 50°F, set it to 62°F). This minimizes the drastic temperature drop if a false "Away" trigger occurs.
5. Disable Auto-Schedule (Optional): If you prefer a fixed routine over a learning one, go to Settings > Auto-Schedule and toggle it OFF. This forces the device to stick strictly to the manual calendar you program.

If That Didn't Work

• Install Additional Nest Temperature Sensors: If your thermostat is in a hallway but you spend most of your time in a bedroom or office, the built-in sensor may not "see" you. Pair a Nest Temperature Sensor (model ASA-S01) in the room you frequent. In the app, go to Settings > Temperature Sensors and select the sensor in your current room as the primary reference for presence.
• Check for Signal Interference: Ensure the thermostat is not placed near a drafty window or a heat-producing appliance (like a lamp). This can confuse the internal sensors, making the device think it is in a different environment, which can occasionally trigger erratic Home/Away behavior.
• Disable "Eco" entirely: If you have a specific medical need or pets that require a strict temperature, go to Settings > Home/Away Assist and uncheck the box for "Eco temperatures". This prevents the device from ever switching to the energy-saving mode, regardless of whether it thinks you are home or not.
• Update Firmware: Ensure your device is on the latest version. Go to Settings > Software. If an update is available, trigger it immediately, as Google frequently releases patches for the occupancy sensor's sensitivity and geofencing logic.

Heads Up

• Battery Optimization: On Android devices, ensure the Google Home app is excluded from "Battery Optimization" or "Sleep mode," otherwise the geofence will fail and trigger Eco mode.
• The 2-Week Window: If you re-enable Auto-Schedule, remember that it takes approximately 14 days of consistent manual adjustments for the device to build a reliable pattern. Avoid changing the temp every 30 minutes during this phase.
• C-Wire Importance: If your thermostat is power-cycling or losing Wi-Fi connection, it may "forget" your presence status. Ensure you have a C-wire (Common wire) installed to provide constant 24V power; otherwise, the device may enter a low-power state that disables sensors.