How To Unlock A Honeywell Pro Series Thermostat T4 T6 Pro

On the 8000 series, hold down the “System” and “Auto” options, then hold the blank lower center button.

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.

On the 8000 series, hit “Done. ”

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.