How thermostat keypad lock works
Most thermostats lock from a menu or app setting, and you unlock them the same way. Honeywell Home T4 Pro and T6 Pro thermostats use the LOCK menu with the code 1234. Google Nest and ecobee use a PIN or security code you choose. Sensi locks and unlocks only from the Sensi app.
What does a keypad lock do?
A keypad lock stops people from changing the thermostat at the wall. It is meant for rentals, offices, shared homes and curious children. The heating and cooling keep running normally; only the buttons or touchscreen are restricted.
Most locks come in two strengths. A partial lock leaves the temperature adjustable but blocks the mode, the fan, the schedule and the menus. A full lock blocks everything. Some brands replace the partial lock with a temperature range: people can still adjust, but only between a low and a high number you pick.
If you are standing in front of a thermostat that will not take your changes right now, start with thermostat screen locked, which helps you work out which lock you are dealing with. This page covers how each lock is set up and turned off.
| Thermostat | Where to lock and unlock | Lock levels | Code |
|---|---|---|---|
| Honeywell Home T4 Pro and T6 Pro | Menu, then "LOCK" | "OFF", "PART" (temperature only) or "ON" (no access) | "1234" |
| Honeywell Home T9 | Menu, then Security, then "Change lock mode" | Unlocked, Partially locked (temperature only) or Fully locked | Optional password you create |
| Honeywell Home VisionPRO TH8000 | Advanced function 0670 | 0 unlocked, 1 temperature controls and CANCEL only, 2 fully locked | Not stated |
| Google Nest Thermostat E and Learning Thermostat (3rd and 4th gen) | Thermostat Settings, then Lock; or the Nest or Google Home app | Locked to a temperature range or a single temperature | 4-digit PIN you choose |
| ecobee | Main Menu, then Settings, then Access control | Not stated on the page we checked | Security code you set |
| Sensi | Sensi app only: settings gear, System settings, "Keypad Lockout" | On or off; all buttons disabled | None; your Sensi app account |
| Amazon Smart Thermostat | Not stated | Not stated | Not stated |
How do you lock or unlock a Honeywell Home thermostat?
On the T4 Pro and T6 Pro, press Menu, use the arrows to reach "LOCK", press Select, then choose "OFF", "PART" or "ON" and press Select again. To unlock, press the center button and enter "1234": change the first digit with the arrows, press Select, repeat for the next three digits, then press Select once more. If the code is wrong the screen flashes "--", and Back takes you a step back to try again.
The menu item is not always there. Honeywell changed this feature: on original T4 Pro and T6 Pro thermostats (series 0 to 6 on the T6 Pro), installer option 435 sets the lock directly, while on current ones it only enables or disables the user lock. When it is disabled, the LOCK item is missing from the menu.
The T9 handles it on the touchscreen: Menu, Security, then "Change lock mode" or "create password". Honeywell suggests writing the password down. The VisionPRO TH8000 sets its lock through advanced function 0670.
Two Honeywell features look like a lock but are not. The VisionPRO SCREEN button locks the screen for 30 seconds so you can wipe it, and the T9 has a similar "Clean Screen" option with a countdown. Both end on their own.
How do you lock or unlock a Google Nest thermostat?
Google's lock page applies to the Nest Thermostat E and the Nest Learning Thermostat. On the thermostat, press the ring, open Settings, choose Lock, enter a 4-digit PIN twice, then set the lowest and highest temperature people may choose. A lock icon appears at the bottom of the screen.
In the Google Home app, open the thermostat's settings and tap Lock. Google gives a smallest range of 5°F when you lock from the app; on the thermostat in Heat•Cool, the smallest is 2°F. To unlock, press the ring and enter the PIN, or tap Unlock in the app. The app does not ask for the PIN, but the thermostat must be online.
A locked Nest still follows your schedule and Eco temperatures, even outside the locked range.
How do you lock or unlock an ecobee or a Sensi?
On an ecobee, the setting is under Main Menu, Settings, Access control, and you turn it off by tapping "Disable Security Code" once you have the code. ecobee says a thermostat protected by a security code will not let you control all of its settings.
Sensi does it differently. Keypad lockout can only be turned on or off in the Sensi app: tap the thermostat's name, the settings gear, then System settings, and toggle "Keypad Lockout". A small lock icon appears in the app and on the thermostat, and every button is disabled except the backlight button on the Sensi Smart. There is no code to enter at the wall.
Is a lock the same as a temperature limit?
No, although the result can feel similar. A temperature limit caps how far the setpoint can go while leaving everything else open. Sensi's Temperature Limits, set in the app under System settings, show "Limit" on the thermostat when someone tries to go past them, and they cannot be changed at the wall. On Honeywell Home T4 Pro and T6 Pro thermostats, installer options 430 and 431 set the lowest cooling setpoint (default 50°F) and the highest heating setpoint (default 90°F).
The Amazon Smart Thermostat help pages we checked do not describe a lock or limit setting. For temperatures that change by themselves rather than refusing your input, see thermostat schedule periods.
What if you do not know the code?
On a Honeywell Home T4 Pro or T6 Pro, the guides give "1234". On a Nest that is online, unlock it from the app; Google says to contact its support if the thermostat is offline and you do not have the PIN. ecobee suggests asking the previous resident or landlord first, then calling ecobee support with a photo of the serial number from Main Menu, About; releasing the code can take up to 24 hours. A Sensi needs the app account it is registered to.
Frequently asked questions
- What is the default unlock code on a Honeywell Home T6 Pro?
- Honeywell's T6 Pro and T4 Pro user guides give the password "1234". You enter it one digit at a time with the arrow buttons, pressing Select after each digit and once more at the end. A wrong code makes the screen flash "--".
- Can I lock my thermostat but still let people change the temperature?
- On many models, yes. Honeywell's "PART" setting on the T4 Pro and T6 Pro, and "Partially locked" on the T9, leave only the temperature adjustable. A locked Google Nest lets people turn the ring within the range you set. Sensi's app lockout is all or nothing.
- Why is there no LOCK option in my Honeywell menu?
- The installer controls it. On current T4 Pro and T6 Pro thermostats, installer option 435 enables or disables the lockout feature, and when it is disabled the LOCK item does not appear in the menu. Ask whoever installed the thermostat.
- Does a locked thermostat still follow its schedule?
- Google says a locked Nest still heats or cools to the temperatures in your schedule and follows your Eco Temperatures, even when they fall outside the locked range. The other manuals we checked do not say a lock pauses the schedule.