how do i get my remote sensor to actually control the temperature? it's paired but the thermostat seems to ignore it.

Diagnosis

The Honeywell Home T10 Pro utilizes a "Participation" logic system, meaning that simply pairing a remote sensor to the thermostat does not automatically make it a temperature controller. By default, the T10 Pro is configured to rely solely on the internal temperature sensor located within the main wall unit. When a remote sensor is paired, it exists in the system's database, but it remains in a "passive" state unless explicitly assigned to a specific Comfort Setting (such as Home, Away, or Sleep).

If your sensor is paired but ignored, it is because the "Participation" toggle for that specific sensor is turned off for the current active period. The thermostat is continuing to read the temperature at the wall unit and ignoring the remote data. You can confirm this by checking the main screen; if the temperature displayed is the temperature of the hallway (where the thermostat is) rather than the bedroom (where the sensor is), the sensor is not participating in the current thermal loop.

How to Fix It

To activate the remote sensor and force the T10 Pro to prioritize its reading, follow these exact steps on the thermostat interface:

1. Press the Menu button on the main screen to enter the system settings.
2. Navigate to and select Comfort Control. This opens the menu where you manage the different profiles for your day.
3. Select the specific Comfort Setting that is currently active (e.g., "Home" if it is daytime, or "Sleep" if it is nighttime). Note that you must repeat this process for every profile you use, otherwise the sensor will stop working when the thermostat switches from "Home" to "Sleep."
4. Within the selected Comfort Setting, select the Participation option.
5. You will now see a list of all available temperature sources: the "Thermostat" and your "Remote Sensor(s)" (often labeled by the room name you assigned during pairing).
6. Tap the checkbox or highlight the Remote Sensor you wish to use. Ensure the checkmark is visible.
7. If you want the thermostat to average the temperature between the wall unit and the sensor, keep both checked. If you want the thermostat to ignore the wall unit entirely and only follow the sensor, uncheck the "Thermostat" option and leave only the remote sensor checked.
8. Press Done or the back arrow to save the settings and return to the main screen.

If That Didn't Work

• Check for Signal Interference: If the sensor is checked for participation but the temperature isn't updating, the sensor may be out of range or blocked by dense materials like foil-backed insulation or thick masonry. Move the sensor within 30 feet of the T10 Pro wall unit to see if the temperature reading begins to fluctuate. If it does, you may need a signal repeater or a different mounting location.
• Perform a Hard Sensor Reset: Remove the battery from the remote sensor, wait 30 seconds, and re-insert it. Then, go back into the Menu > Sensors list and verify that the sensor status shows as "Online." If it shows "Offline," the participation settings will be ignored regardless of your selections.
• Verify Battery Voltage: Low batteries in T10 sensors can cause them to maintain a pairing link but fail to transmit temperature packets frequently enough to trigger the HVAC system. Replace the batteries with fresh high-quality alkaline cells; avoid using rechargeable batteries as they often have a lower nominal voltage (1.2V vs 1.5V) which can cause intermittent connectivity.
• Factory Reset the Sensor: If the sensor is "ghosting" (appearing paired but not communicating), remove it from the thermostat via the Sensors menu. Then, press and hold the pairing button on the sensor for 10 seconds until the LED flashes, and re-pair it from scratch before re-assigning the Participation settings.

Heads Up

• Averaging Logic: When multiple sensors are selected for participation, the T10 Pro calculates the average temperature of all selected points. This can lead to the HVAC running longer than expected if one room is significantly colder than the others.
• Battery Life: Remote sensors typically last 2 years, but if you have a very high-frequency polling rate or extreme temperature swings, check them every 12 months to avoid unexpected system shutdowns.
• Placement Warning: Never place a remote sensor in direct sunlight or directly in the path of an AC vent. This will cause "short-cycling," where the thermostat thinks the room is cooled/heated instantly and shuts off the system before the rest of the room reaches the set point.
• Naming Conventions: Always name your sensors (e.g., "Master Bedroom," "Nursery") immediately upon pairing. If you have multiple sensors, it becomes nearly impossible to troubleshoot Participation settings if they are all labeled "Sensor 1," "Sensor 2," etc.