GadgetsSmart Home

How To Unlock a Honeywell Thermostat

Thermostat Gauge

A thermostat is a crucial home gadget that keeps your family, tenants, and guests comfortable by regulating the indoor temperatures. With a few button clicks, the gadget triggers, monitors, and controls your house’s heating and cooling processes. The gadget is especially vital during those cold winter nights and the unpleasant summer days. 

Quick Answer

Honeywell thermostats are one of the widely-used brands in many homes because of their remarkable features and being up to the task. They are lockable to prevent third parties from altering your settings. 

Did you or someone else lock a Honeywell thermostat, and you want to unlock it? We have prepared this step-by-step guide to unlock Honeywell thermostats.

Reasons for Locking a Honeywell Thermostat

Honeywell thermostats have three lock settings; On, Off, and Part. Let us look at each setting in detail:

On (Full Lock)

No one can access the settings when the lock settings are “On” on your thermostat’s display. They can’t alter your temperature regulation settings unless they have the passcode to unlock the thermostat. 

Part (Partial Lock)

A partially locked thermostat allows changing some settings, such as the temperature. To access the other settings on the keypad, the user needs to input the correct PIN, password, or code.

Off (Unlocked)

Anyone can access and alter the settings when your thermostat is fully unlocked and showing the “Off” icon.

The manufacturer had valid reasons to put these settings because they are aware of the need for locking and unlocking a thermostat. But why would anyone need to lock their thermostat? We look at some of the common reasons below:

  • You have nosy kids who are always tampering with the settings on your thermostat.
  • You are a landlord and don’t want tenants changing the settings on the thermostat to save on energy bills.
  • You are an Airbnb host who wants control over the house without going back and forth with guests.

How To Unlock Honeywell Thermostats

To unlock a Honeywell thermostat, you need to input the correct passcode. The input process varies from one model to another. 

Below are the unlocking techniques for each model:

Unlocking the Honeywell T4 Pro Series

Follow the below steps to unlock your Honeywell T4 Pro series thermostat:

  1. On the keypad menu, press the “Unlock” button.
  2. The thermostat will prompt you to enter a passcode/PIN. The correct code is 1234.
  3. Press the (-) and (+) buttons to key in the four numbers until you get the correct number.
  4. Press “Select”.
  5. Repeat step 3 until you enter the four correct digits. If you enter the code correctly, the thermostat will unlock.

Unlocking the Honeywell T6 Pro Series

The T6 Pro series has a touchscreen feature and a slightly different unlocking process. When the thermostat is locked, you can see a lock symbol on the screen. Below are the steps to unlock this model:

  1. Press the “Lock” icon on the screen. A prompt to input the passcode appears.
  2. You need to remember the passcode to proceed with this step. That is why it’s essential to write down or memorize the passcode when locking your T6 Pro Series thermostat. Use the (+) and (-) signs on display to input the correct four-digit code.
  3. After you get the correct digit, press “Select”.
  4. Repeat steps two and three until all four digits are correct. If the passcode is right, the thermostat unlocks, and all the settings on the home screen become accessible.

What To Do if You Forget the Passcode

Writing down or memorizing the four-digit code is advisable if you frequently lock your thermostat. In the event you completely forgot the password, follow the following steps to unlock your thermostat:

  1. Open your thermostat’s faceplate and look for a four-digit code at the top right corner of the gadget.
  2. Your thermostat’s PIN is the sum of that code and 1234. For example, if the code is 1000, your PIN is 2234.
  3. After obtaining the PIN, follow the usual steps of unlocking the thermostat.

Unlocking the Honeywell 8000 Series

Honeywell 8000 thermostat and related models have a complex user interface and can be challenging to unlock, especially if you didn’t lock it yourself. When locked, the display will read locked. When unlocked, the program reads 0670. 

Below are the steps to unlock this type of thermostat:

  1. Simultaneously hold down the “System” and “Auto” buttons on display.
  2. On the lower part of the screen, press the center button for some time until the program opens (until the screen allows you to change the figures on the left). For some models, you press the second and fourth buttons simultaneously instead of the center button.
  3. Use the up and down arrows on the center of the display to change the program to 0670.
  4. Use the up and down arrows on the right to change the value on the right to 0.
  5. Press “Done”. The thermostat unlocks to give access to all settings.

Unlocking the Honeywell VisionPRO Series With RedLINK

Follow these steps to unlock Honeywell VisionPRO thermostats with the R suffix:

  1. Press “Menu”.
  2. Use the arrow buttons on display to find the “Settings”.
  3. Tap “Select”.
  4. Use the up and down arrow buttons to key in the four-digit passcode.
  5. Press “Done”. The thermostat unlocks, giving you access to all settings on the keypad.


There are several reasons to lock your thermostat, from preventing nosy kids from tampering with the device to maintaining a certain setting to save energy costs. 

The Honeywell thermostat has three lock modes; unlocked, partial, and full lock. The unlocking process varies from one model to another, but most require a four-digit passcode.

Frequently Asked Questions

How do I override a Honeywell thermostat?

You may need to override a thermostat when the temperatures are annoying, but you cant unlock the thermostat. Follow the following steps to override your thermostat.

1) Press and simultaneously hold the Display key and the Off button.
2) Release the Off button but keep pressing the Display button.
3) Tap and hold the Up key while still pressing down the display button.
4) Finally, release the Display and Up keys together. This process overrides the thermostat allowing you to control it manually for some time.

Can I unlock a Honeywell thermostat without a code?

It depends. Most Honeywell thermostats require a four-digit passcode to unlock. However, some smart models like the Honeywell 8000 series only need a program change to unlock.

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