Troubleshoot E10, E30, E66, E80, E116, E160, E196 and M13 errors

Learn what causes these errors 

The Nest thermostat is designed to work in most cases without a common wire. Instead of using a common wire to keep your thermostat charged, your Nest thermostat can use the Y1 (air conditioner) wire to power itself.

If your air conditioner stops sending power to your thermostat, your thermostat can let you know with one of these errors. There are a number of reasons why your air conditioner might stop sending power to your thermostat. Below we list some possible reasons, but it’s important to contact a professional to diagnose your system and determine what the root cause of the error is.

One possible reason is that your system needs maintenance. If your system breaks down, it will likely stop sending power to your thermostat. An HVAC professional can help determine if your system needs repair.

Another possible reason is that you live in an area that experiences very cold temperatures in winter. Your air conditioner may come equipped with a safety device that will stop it from turning on in extremely cold weather to prevent damage. These safety devices, sometimes called low pressure switches (LPS) or safety cut-out switches, can sometimes prevent your air conditioner from providing your Nest thermostat with power in extremely low temperature conditions.

If you see one of these errors (E10, E30, E66, E80, E116, E160, E196 or M13), you can use the quick fix below to help get the heat back on. Then, when it's convenient, call an HVAC professional such as a local pro to come take a look at your system and install a common wire.

Troubleshoot to get heating back on

1. Turn off the power to your heating and cooling
system at the main breaker for your home.
thermostat breaker
2. Grip the ring of your thermostat and pull it gently
towards you away from the wall. Your thermostat
should pop right off the base.
remove display

3. Take a picture of your wiring in case you need it later.

4. Remove any Y wires (Y, Y1, Y2) from the Nest base.
Then, if you have both Rc and Rh, remove the Rc wire
as well.

Tip: You can remove a wire by pressing down on the
button next to the connector while gently pulling on
the wire.

5. Wrap the exposed end of each wire you removed
with electrical tape so it won't touch any other wires.

6. Put the display back on the base. Make sure the
wires behind are pressed down towards the wall.
Your thermostat should click firmly into place.

remove wires

7. Turn your breaker back on and see if your Nest
thermostat is able to get power from your HVAC system.

If your Nest thermostat powers on without an error,
you should be able to turn on the heat. If it does, read
below to learn about your next steps: Installing a
common wire.

Note: You may see the message "The wiring to your
equipment has changed." If you do, select Continue
  Continue  Continue  Done.

Important: You won't be able to use your AC until you reconnect
your Y1 wire. You should install a common wire and reconnect
your Y1 wire to continue using your Nest thermostat

8. If your Nest thermostat doesn't power on, remove the display
and try to change it with a micro USB cable. Plug the USB into the
back of your thermostat display. Charge the display for 5-10 minutes,
you should see the display power on. Put the display back on the
Nest base. 

thermostat breaker

Install a common wire to prevent future problems

With your HVAC system configuration, it is recommended that you have a professional install a C or common wire to prevent power issues in the future.

Tip: You may already have an unused wire behind your thermostat that can be used as a C wire. An HVAC professional such as a   local pro should be able to repurpose this wire into a new C wire without needing to run a new wire to your thermostat.

Contact an HVAC professional or a   local pro to learn more about having a common wire installed. After a common wire installed, your professional installer will be able to reattach the Y1 wire to your Nest thermostat. Once the Y1 wire is reconnected, you can continue using both your heating and cooling systems.

Note: Nest Pros are a network of independent companies or contractors and are not employed by Nest.

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