How to Unlock a Honeywell Thermostat

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Trying to adjust your Honeywell thermostat, but finding that you’re locked out? You’re not alone—many people are puzzled by the locking function on this important tool in their home. Fortunately, unlocking the thermostat is easy, and can be done in just a couple of steps. Keep reading to learn how to unlock your Honeywell thermostat and adjust the lock settings in under a minute.

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1

Press the center button.

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  1. The center button will have a small “Unlock” label on the screen, right underneath the temperature reading. Hit that button to go to the next screen. [1]
    • On the 8000 series, hold down the “System” and “Auto” options, then hold the blank lower center button.
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2

Use the + and - buttons to enter the 1234 pin.

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  1. Once you hit “unlock,” you’ll be taken to a new, blank screen that’s waiting for you to input your pin. Use the + button to add a number, and use the - button to subtract a number. [2]
    • Once you’ve entered a number, hit “Select” to move to the next digit.
    • Most Honeywell thermostats come with a default passcode of 1234. Some models let you change the pin in the security settings, while others don’t.
    • If you have an 8000 series, the passcode is 0670.
3

Hit “Select.”

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  1. Once you’ve got your passcode entered in, simply hit “Select” one more time. Now your thermostat is unlocked, and you can change the temperature or adjust the settings to your liking. [3]
    • On the 8000 series, hit “Done.”
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4

Press “back” to try again.

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  1. Entering the wrong passcode will bring you to a new screen that just says “---”. On that screen, hit the “back” button to go back and re-enter the passcode. [4]
5

Lock the thermostat in the main menu.

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  1. From the thermostat’s home screen, press “Menu,” then hit the + or - buttons until the screen says “LOCK.” Hit “Select,” then choose which lock setting you’d like your thermostat to be on. Settings include: [5]
    • OFF : The thermostat is unlocked, and full access is allowed.
    • PART: The thermostat is partially locked, and only the temperature can be changed.
    • ON: The thermostat is fully locked, and will have to be unlocked for any changes.
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      Tips

      • If you forgot your code, take the thermostat off the wall and look for the number on the back of the device. Find that number, then add 1234 to it. That number will bypass your passcode and let you into the thermostat.
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      References

      1. ↑ https://www.honeywellhome.com/us/en/support/how-do-i-lock-unlock-the-screen-th4210u2002-th4110u2005-thermostat/
      2. ↑ https://sierracoolslv.com/wp-content/uploads/Honeywell-T4-Pro-User-Guide.pdf
      3. ↑ https://manuals.plus/honeywell/honeywell-home-t4-pro-thermostat-manual
      4. ↑ https://sierracoolslv.com/wp-content/uploads/Honeywell-T4-Pro-User-Guide.pdf
      5. ↑ https://sierracoolslv.com/wp-content/uploads/Honeywell-T4-Pro-User-Guide.pdf

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      Reader Success Stories

      • Robert W.

        Jan 21

        "Just a simple story of locking the thermostat, didn't know the code. wikiHow instructions solved my problem."
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