Honeywell Thermostat Not Working After Battery Change [FIXED]

Thermostats can be tricky, and this guide aims to make the task of changing a thermostat battery a bit easier. Thermostat batteries can last anywhere between 1-5 years depending on the manufacturer and model of your thermostat.

If your Honeywell thermostat is not working after replacing the battery, then you will want to try a few troubleshooting options to resolve the problem.

The Honeywell room thermostat takes the guesswork out of temperature control by recommending and enacting temperature adjustments based on a combination of user preferences and outside weather conditions.

Its time-saving features — like the automatic Vacation Hold function, which prevents your heating and cooling system from switching on and off thus saving you money — make it a quick favorite with homeowners.

With your current thermostat, you’ll need to replace the battery every year or two. Although easy to change the battery, the old batteries need to be removed and replaced — not a terrible process, but certainly cumbersome when you have to consider that you’ll have to do this eventually.

You need to make sure the right type of batteries are installed. Most batteries are not interchangeable, so if you are not using the right ones, the thermostat will not work correctly.

Customers report that the Honeywell thermostat does not work after battery replacement. Though the issue is rare, it can certainly be resolved by troubleshooting the problem carefully. Here are some steps you can take to rectify the malfunctioning thermostat after battery change.

Honeywell Thermostat Not Working After Battery Change – Troubleshoot And Diagnosis

Honeywell Thermostat Not Working After Battery Change

There’s a lot that has to be done before you get the best out of your Honeywell thermostat. If you’re having any issues with it, don’t worry. We have got you covered. In this ultimate guide, we will go through all the problems you might face setting it up and also teach you how to deal with them.

1. Use Correct Type Of Batteries

If you’ve tried replacing your batteries in the Honeywell thermostat but are still having issues with the unit, try fresh batteries. Also, check to see if you have the correct type of batteries — make sure they’re recommended batteries. Putting in incorrect batteries is a common reason why this device doesn’t work properly after a battery change.

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There are multiple factors that you should consider when choosing the right batteries for your thermostat. A simple way to do this is to check the inside of the battery compartment. Most batteries require a 1.5v AA alkaline battery.

2. Replace All Battery At Same Time

Batteries should always be replaced in a thermostat at the same time, because there might be differences in charge levels between the old one and the new.

Differences in charge levels can make your thermostat show incorrect temperatures or fail to operate altogether.

You should ensure that the replacement batteries are in the same charge level. If not, your thermostat might have issues registering the correct temperature and you may experience weird results in your home.

3. Make Sure That You Install The Battery Correctly

Make sure the batteries are installed correctly. Take care not to mix up the positive and negative ends of the batteries. This can affect how your thermostat operates, which will lead to you not being able to adjust the temperature accurately.

To replace the batteries, first shut off the power to your thermostat. Next, open the battery compartment to remove the old batteries.

Then, insert two new AAA batteries in the compartment with the correct polarity. Finally, flip the switch back to on and let your thermostat do its work.

If you follow the instructions, the batteries should go in so that the + and – designations on the battery correspond to the + and – markings inside of the battery compartment.

4. Factory Reset the Thermostat

There are many reasons why you may need to reset your thermostat. Sometimes, strange quirks can occur and you may find yourself unable to change these settings. Other times, you may want to get back to the default settings of the thermostat.

A factory reset can be done using either the physical buttons on the device or by using its web portal. However, if you use either of these methods, all of your personal data will be deleted.

In Order to reset the Thermostat, Do the Following:

Open the door to the compartment containing batteries. Insert your coin or other object into the slot to pop out the compartment door.
Remove the old batteries (follow the polarity markings in the battery holder) and replace them.
Replace the door and turn your thermostat back on!

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To learn how to reset your thermostat, follow these steps:

  1. Remember to turn your thermostat off before proceeding further.
  2. Push the coin into the slot either by sliding it in and then pulling it out, or by using a flat object to press down on the coin’s head. Then, open the battery compartment door.
  3. Now remove the batteries from the thermostat.
  4. Put the batteries back in the thermostat battery compartment, turning them in the opposite direction from what they originally were. The labels on the battery holder will indicate which way is correct.
  5. Keep the batteries like this for five seconds.
  6. Next, remove the batteries from the thermostat. Then reinsert them, ensuring they are aligned with the correct polarity.
  7. The thermostat display now lights up, meaning it is back on.

Factory Reset Honeywell Thermostat T5+, T5, and T6

  1. Ensure that your thermostat is turned on.
  2. Hold down the Menu button for about fifteen seconds.
  3. Navigate left to the Reset option.
  4. Choose Factory Reset by selecting it.
  5. Confirm your selection by pressing Yes or OK.
  6. Your thermostat has now been reset.

5. Wiring Issues

If your thermostat is displaying an error code, try to reset it and check if the problem resolves. If the problem still occurs, it may be caused by a wiring issue and you’ll need to call a professional HVAC contractor.

For example, there could be a loose connection between your thermostat and the wires leading to your wall outlet. A simple disconnection could cause a serious issue, since you won’t be able to turn the temperature down once you start cooking.

Specifically, remove the wires from the wall and check that the connector is securely connected to both wires. Also make sure that any excess wire is not interfering with other components.

6. Ensure That Door is Closed Properly

There’s nothing more frustrating than a thermostat that doesn’t work. Especially one where the furnace won’t turn on, or the thermostat keeps turning itself back off. This is a simple problem to fix; check your furnace access door and make sure it’s closed all the way.

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7. Check Circuit Breaker/Fuse

If the Honeywell thermostat goes out in the aftermath of a power surge, fuse blowout, or circuit breaker tripping incident, it will not switch back on after changing its batteries unless you go through the process of replacing your house’s blown fuse or resetting your home’s relevant circuit breaker.

First, open up your fuse box and replace the blown fuse with a fresh one.

How To Reset Honeywell Thermostat After Replacing Batteries

Let’s take a look at how to perform a thermostat reset:

Put the thermostat in the ‘OFF’ position and remove the batteries.

Swap the batteries’ polarities — put them in with negative (-) on positive (+), and positive (+) on negative (-).

Wait 10 seconds then put the batteries back in their original positions.

The thermostat will be reset to factory settings.

Honeywell Thermostat Won’t Turn ON After Replacing Batteries

When your Honeywell thermostat stops working, you might think it’s a battery problem. But before you change the batteries, make sure that they are the right type and are put in correctly. If that doesn’t work, try a factory reset.


If none of the previous solutions work, you might have an issue beyond your control. If a problem is too complex to diagnose with your equipment, or if it risks damage to a more expensive part, it may be safer and cheaper to get the professionals in.

You have spent a good amount of money to purchase your thermostat, so you should make sure it is working at its best.
A lot of people think that if their thermostat fails, it needs to be replaced immediately. However, that is not always the case. Sometimes your smart thermostat only needs a good cleaning or perhaps a battery replacement — especially if it’s been sitting idle for some time.

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