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Unlocking the Honeywell T4 Pro Thermostat


Have you ever accidentally locked your Honeywell T4 Pro Thermostat? Well, you’ve come to the right place! To help, we’ve put together a step-by-step video explaining the process of how you can unlock your Honeywell T4 Pro Thermostat!






1) From the locked home screen, press the center button.
2) Enter the passcode. The default passcode when the Honeywell T4 Pro is partially or fully locked is 1234. Press the Plus or Minus buttons to change the first digit of the passcode, then press the Select button. Repeat these steps until 1234 is displayed on the screen.
3) Press the Select button. The thermostat will now be unlocked. If the incorrect passcode is entered, lines will flash on the screen. Press the Back button, then follow the previous steps to enter the correct passcode.



For complete instructions and a demonstration, watch this video:

Browse our selection of thermostats, including the Honeywell T-Series at

Posted in All Posts, How Tos + Tricks, Products |

16 Responses to Unlocking the Honeywell T4 Pro Thermostat

  1. kyle says:

    How do you change the password?

    • Raquel says:

      Hi Kyle,

      Unfortunately you cannot change the password on this thermostat. Sorry for any inconvenience!

      • Shawn says:

        There is no point to a password if you can’t change it from the default, the lock feature is pointless as you cannot actually lock anyones access out since the password is readily available online, useless feature

  2. After i enter 1233 and hit select, it does not say lock, but still won’t go over the previous set time

    • Gregory says:

      Hi Adam,

      We’d recommend that you confirm that your thermostat is the same model as the one in the video. Other models may have different passcodes. If you are trying to override the programmed setpoint on a thermostat the is not locked, you should be able to use the plus and minus buttons to adjust the temperature.

  3. Kevin says:

    Why would you make a passcode as simple as 1234 and not make an option to change it.

    • Gregory says:

      I’m sorry that you find it frustrating to not have the ability to change the passcode. This is something that has been brought to Honeywell’s attention numerous times, so hopefully they will listen to valued and concerned customers like you and implement your feedback. If you have any questions at all about your thermostat, please don’t hesitate to reach out to us. Thanks!

  4. Adam says:

    There is no “prog” option after selecting “menu.” I have unlocked the thermostat and can change everything else, but see no “Prog” option no matter what I do. I’ve seen other people answer this question, but haven’t seen anyone report back a solution yet. Any thoughts other than unlocking or contacting Honeywell?

    • Gregory says:

      Hi Adam. Unfortunately, your best option would be to contact Honeywell at 800-468-1502 so that their technicians can help you diagnose your specific issue and find a way to resolve it.

  5. Adam says:

    I called Honeywell and they gave me instructions on how to get “Prog” back when it is disabled (not there.) Since other people have asked the question, but not reported the solution, here it is:

    Hold “menu” and “+” until the screen changes. 120 & 0 will be displayed. I want my schedule to be the same all week so I was instructed to hit “2” to make a M-F & Sat-Sun setup. I hit menu again and when I got back to the main screen (and hit menu again) I was able to get to the program. Hope that helps anyone else having the same issue.

  6. Connie Morreale says:

    i was pressing all kinds of buttons when i first got this thermostat and accidentally locked it. i have no clue what code i entered.what do i do?

    • Gregory says:

      Hi Connie. The best solution for this would be to contact Honeywell Customer Care directly (1-800-468-1502) and speak with them about unlocking the thermostat. Hope this helps!

  7. Steve says:

    Connie Morreale, I did same thing but figured it out. Enter the default passcode of 1234 but then hit “Select” instead of Home. The instructions say this but I missed it, maybe you did, too?

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