Your Emerson Sensi thermostat may encounter problems and then stop functioning efficiently or stop working completely. When this happens, you want to fix the problem as soon as possible but you don’t know whether you’ll be able to troubleshoot and fix the problem yourself. 

Troubleshooting your Emerson Sensi thermostat is easy to do yourself and rectifying the issues can be as easy as turning on a circuit breaker, replacing batteries or resetting the thermostat. Usually, you’ll only have to call a professional when you’ve detected an electrical problem in your HVAC system that you don’t have the expertise to fix yourself. 

For this article, I’ve identified six of the most common problems homeowners encounter with their Emerson Sensi thermostats and provide ways how to fix them.

Heat pump smart thermostat
Emerson Sensi – Smart Thermostat for Heat Pump

Problem 1: Your Emerson Sensi thermostat is not working and the display is blank

If your Emerson Sensi thermostat is not receiving power, it will not work. Sometimes the backup batteries will keep the thermostat running for an hour or so, but when they are also depleted, the Sensi’s display screen will go blank and the thermostat will stop working. 

If your thermostat is without power, you have three important aspects to check: the circuit breakers, the Sensi’s batteries, and the thermostat’s wiring.

A) Circuit breakers

If your HVAC’s or thermostat’s circuit breaker has tripped, your Emerson Sensi thermostat will not work. Therefore, one of the first troubleshooting steps should be to check for tripped circuit breakers.

Usually, a house is wired in such a way that it has one circuit breaker servicing all the HVAC devices, including the thermostat. Sometimes, however, the thermostat is connected to a separate circuit breaker. Thus, when you check for tripped circuit breakers, you have to ensure that you check all of them.  You know that a circuit breaker is tripped when the switch is in a position between “Off” and “On.” 

The circuit breaker might have tripped because of a power surge.  If you find that the circuit breaker has tripped, turn it on again. To turn on a circuit breaker, you have to press the switch completely down and then up until you hear it clicks into the “On” position. Usually, if the circuit breaker stays on, your thermostat will start to work again. 

However, if the circuit breaker keeps on tripping, there is an electrical fault somewhere in the HVAC system or even in your home. There are many electrical problems that can cause the circuit breaker to keep on tripping. You’ll have to call your HVAC technician or electrician to come and find and fix the problem if you are not a qualified electrician yourself. 

B) Batteries

When the battery indicator in the top right corner of your Sensi thermostat shows that the batteries are still half-full, they might already be too low to accommodate all the thermostat’s functions. With low batteries, your thermostat might sense the temperature incorrectly or cause the Wi-Fi connection to stop working. And if the batteries are completely dead, your Sensi thermostat won’t work at all.

So, when the indicator is below the halfway mark, it is a good policy to replace the batteries, especially if you haven’t replaced them during the last 12 months. Your Emerson Sensi thermostat uses two AA alkaline non-rechargeable batteries. Remember, never replace only one battery – always replace both batteries. 

The battery replacing process for your Emerson Sensi is simple: 

  • Use both hands and carefully pull the face plate towards you.
  • After removing the face plate, turn it over and remove the batteries.
  • Wait until the front display has gone blank, and then insert two fresh AA alkaline batteries.
  • Replace the thermostat back on the wall. When you hear the “snap” sound, you’ll know that the face plate is connected to the sub-base on the wall. 
  • Put the power back on.

If low batteries have been the issue, your thermostat will now work again. 

C) Wiring

Loose wires can cause your Emerson Sensi thermostat to stop working.  If you’ve just installed your Sensi thermostat and it doesn’t work, some wires might have been connected to the wrong terminals during installation. 

Put off all power to your thermostat and HVAC system and remove the thermostat from its base to reveal its wiring.  Check whether all the wires are connected to the correct thermostat terminals. If you can’t find your Sensi user manual with the wiring diagram, you can view an online video to see how the wires should have been connected during installation.

How to wire sensi thermostat

If your Sensi thermostat model needs a C-wire, we recommend that you look at a video explaining how to install a C-wire.

How to install a C-wire

Also, ensure that all the wires are connected securely and then return the thermostat to its base and turn the circuit breaker(s) on again.

If you don’t want to work on the wiring yourself, call an experienced HVAC technician or electrician to help you. The technician should be able to detect and fix all the wiring issues that may cause your Sensi thermostat to malfunction.

Problem 2: Your Emerson Sensi thermostat’s display and buttons are not responding

Keypad lockout might be enabled – resolve by disabling the feature

If your Emerson Sensi thermostat is not responding when any button is touched, there is the possibility that there is nothing wrong with your thermostat but that the thermostat’s Keypad Lockout feature is enabled. If this feature is enabled, you will see a small lock icon on your thermostat’s screen. 

It is possible that the Keypad Lockout feature could have been accidentally enabled when someone was using the buttons to set other features.

Fortunately, it is easy to disable this feature. Just press and hold the “Up” button and “Menu” button for 3 seconds. The icon will disappear from the screen, and you can use all the buttons again.

How to disable keypad lockout on Sensi thermostat

Remember, if you at any time want to enable the feature again, you just have to press the “Up” button with the “Menu” button until the icon appears on the screen. 

If not resolved, reset your Emerson Sensi thermostat

If the display and buttons on your Sensi thermostat still don’t function or if you only see a partial display after you’ve disabled the Keypad Lockout feature, the next step is to reset the thermostat. 

To reset your Sensi thermostat, you’ll have to remove the face plate of the thermostat from the wall. Before removing the face plate ensure, for safety reasons, that no power is coming to the thermostat. 

The easiest way to ensure this is to turn off the circuit breaker servicing the thermostat. If the circuit breakers are not labeled, turn off all of them. 

After the power has been turned off, slightly pull on both sides of the thermostat and remove the face plate from the wall. Locate the battery housing and remove the AA batteries. Wait until the display screen goes blank and then reinsert the same batteries. 

Place the face plate back on the wall. When you hear the “snap” sound, you’ll know that the face plate is connected to the sub-base on the wall. 

Put the power back on. (For guidelines on the correct way to turn a circuit breaker on, refer to the section regarding “Circuit breakers” in the discussion of Problem 1 above.)  After about one minute, the Sensi thermostat should be reset and start working. 

If the thermostat is still not working, repeat the resetting procedure, but replace the AA batteries with fresh batteries. If the problem is still not solved, the thermostat might be faulty. Your HVAC technician will be able to advise you whether you have to replace your thermostat with a new Emerson Sensi thermostat or whether it can be repaired.

Problem 3: Your Sensi thermostat is not turning on the AC

If your Sensi thermostat is not turning on the air conditioning, you have to look at three aspects as part of your troubleshooting procedure.

1. Possible power outage in the neighborhood

First of all, ensure that there is no power outage in your neighborhood. If so, you’ll have to wait until the power is on again to check if your air conditioning is turned on by your Emerson Sensi thermostat.  

2. Switches or circuit breakers might be off

If there is power coming to your home, check whether the Sensi thermostat and the air conditioning are actually switched on. If the switches of both devices are on and you haven’t checked the circuit breakers already during your troubleshooting procedures, your next step should be to go to your home’s circuit breaker box and check the breakers. A power surge could have tripped some of the breakers. 

Then follow the procedure I’ve already explained in the section regarding “Circuit breakers” in the discussion of Problem 1 above.

3. Check the furnace door and the wiring at the AC and furnace

Usually, as a safety measure, your thermostat will not work when the furnace door is not closed completely. If it is closed, check the wire connections at the AC and furnace. Remember, if you are not a qualified electrician or don’t have a lot of experience working with electricity, call out an electrician to inspect and fix the wires. 

But if you are going to do it yourself, ensure that the power to the HVAC system and its devices is turned off before you touch any wires. 

Problem 4: Your Sensi thermostat’s schedule is not working correctly

Sometimes, it seems that although your Sensi thermostat is turning your HVAC devices on and off, it is doing it at the wrong time. 

Often the problem is that the “AM” and “PM” settings are incorrectly done.  Ensure that your time settings are correct and that they correspond with the temperature settings you need at the specific times. 

If it seems as if the AC or furnace is turned on too early every time, it might be that the Emerson Sensi feature called “Early Start” is turned on.  

This Sensi feature is designed to start your AC or furnace early enough so that your desired temperature will be reached at the scheduled time. If you don’t want that, you can turn off the feature in the app.

Problem 5:  The cooling and heating are reversed

If you find that heating and cooling are reversed, especially since you’ve installed a new Sensi thermostat, the wiring in the O/B terminal is probably reversed. You can fix the issue by following the next steps:

  1. Press “Menu” on the thermostat, and then “Set Up HVAC Equipment.”
  2. Press “Change settings.”
  3. Switch the setting from “O” to “B” or “B” to “O” and press “Save.”
  4. Go back to the main screen.

Your heating and cooling systems should now work correctly when the thermostat is in either “Heat” or “Cooling” mode. 

Problem 6: Sensi thermostat lost its connection to Wi-Fi

Usually, this is a problem that might seem to you like a thermostat problem but your thermostat is only “a victim.”  

The fault might be your home’s internet

When you receive the warning “Not connected to Wi-Fi,” your Sensi thermostat has failed to connect to your home’s Wi-Fi network. Sometimes the message will read: “Not connected to the Sensi cloud.” Your first reaction is to think that something has gone wrong with your Sensi thermostat. 

This loss of communication is not necessarily your thermostat’s fault. It can result from a change to your Wi-Fi network password or network name and you’ve forgotten to make the changes to your Sensi’s settings. It might also be a home network problem or a poor Wi-Fi signal strength. 

Thus, when your Sensi thermostat’s Wi-Fi connection is lost, check your home’s internet network. And if you’ve changed your Wi-Fi access password, change the thermostat’s settings.  

The fault might be low thermostat batteries

If you’ve checked your home’s internet and Wi-Fi connections and are sure everything is in place and that your thermostat is using the correct username and password, but there is still no Wi-Fi connection, your thermostat’s batteries might be too low. 

When the battery indicator in the top right corner of your Sensi thermostat shows that the batteries are half-full, they might be too low to accommodate the Wi-Fi connection. Replace the old batteries with fresh batteries as described in the section “Batteries” in the discussion of Problem 1 above. Usually, your problem will then be rectified. 

Your router might be too far away from your thermostat

Sometimes, you’ll have to move your router closer to the thermostat to improve the signal strength.


There are common problems that Emerson Sensi thermostat users encounter, but fortunately, most of the issues can be found and fixed by the homeowners themselves. 


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