EcoGuide · Smart Thermostats · Published 2026-10-01 · 800 words

How to Unlock a Honeywell Thermostat: Default Codes by Model

The Short Answer

A lock icon on a Honeywell Home thermostat means the keypad lockout is on. On most button models the default code is 1234. On touchscreen models that ask for a passcode, Honeywell says the code is the thermostat’s date code plus 1234.

Model family	How to unlock	Code
T4 Pro, T6 Pro (TH4110U, TH4210U, TH6xxx)	Press the centre button, enter the code digit by digit	1234
FocusPRO P200 / S200	Press the left centre button until you see 0 and three dashes, then enter the code	1234
Touchscreen models that ask for a passcode	Touch the screen and enter the passcode	Date code + 1234
RTH6350, RTH6450, RET93E, RET95E	No lock feature on these models	–

Sources: Honeywell Home’s T4 Pro lock guide, T6 Pro keypad lockout, FocusPRO keypad lockout and screen unlock article.

What the Lock Levels Mean

Honeywell uses three settings, shown as OFF, PART and ON on button models:

OFF (Unlocked): full access.
PART (Partial): only the temperature can be changed. Mode, schedule and settings are locked.
ON (Full): no changes allowed.

So if you can change the temperature but nothing else, the thermostat is in partial lock, not broken. Landlords and offices often leave it that way on purpose.

T4 Pro and T6 Pro: Unlock With 1234

Press the centre button.
Use + or − to set the first digit, then press Select. Repeat for all four digits of 1234.
Press Select once more to unlock.

If the code is wrong, Honeywell says the screen flashes two dashes; press Back and re-enter the digit. To turn the lock off for good: Menu → LOCK → Select → OFF → Select.

FocusPRO: Unlock With 1234

Press the left centre button until the display shows 0 and three dashes.
Use the arrow keys to set each digit of 1234, pressing Select after each one.
Press Select again to unlock. To change the lock level: MENU → LOCK → SELECT, choose OFF, then SAVE & EXIT.

Touchscreen Models: Date Code Plus 1234

Honeywell’s unlock article gives a formula for touchscreen models that ask for a passcode: add 1234 to your date code. Its example: date code 1632 gives 1234 + 1632 = 2866.

The date code is a four-digit number. On the VisionPRO it is listed under Menu → Dealer Information, and on the T10 under Thermostat Information; it is also commonly printed on the back of the thermostat, so you can pull the unit off its wall plate to read it if the menu is locked.

If 1234 Does Not Work

Someone changed the code. Honeywell’s documents give no user procedure for recovering a changed PIN. Ask whoever set it (a landlord, a previous owner or the installer), or call Honeywell Home support on 1-800-633-3991.
The lock option is missing from the menu. Honeywell notes the keypad lockout only appears in the user menu if the installer set the thermostat up to allow it.
It is not locked at all. A thermostat that ignores button presses and shows no lock icon may have lost power; see black or blank screen. One that says “Wait” is in a compressor delay.
Last resort. A factory reset returns the thermostat to defaults, but on several models the reset menu itself is behind the lock or the installer code.

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Frequently Asked Questions

What is the default code to unlock a Honeywell thermostat?

1234 on T4 Pro, T6 Pro and FocusPRO models. On touchscreen models that ask for a passcode, Honeywell says to add 1234 to the thermostat’s date code.

Why can I change the temperature but nothing else on my Honeywell thermostat?

It is in partial lock, which Honeywell describes as allowing only the temperature to be changed. Unlock it with the code and set LOCK to OFF.

How do I find the date code on a Honeywell thermostat?

It is a four-digit number shown under Dealer Information or Thermostat Information in the menu on some models, and commonly printed on the back of the thermostat.