Troubleshooting Nest thermostat error codes

You might see an error on your Google Nest thermostat or in the app if there’s a problem detected with the thermostat’s wiring or internet connection. Here are some errors you can see and steps you can take to help fix them.

Summer 2019 heat wave troubleshooting

If your Nest thermostat suddenly started showing an E3E4E23E24E73E74 or E195 power error during the hot summer months, visit the following link to learn how to help fix it.

Troubleshooting E3, E4, E23, E24, E73, E74 and E195 errors >

If you see any other thermostat error, read below.

 

 

T error codes

How to troubleshoot T errors 

You’ll see a Nest thermostat T error when running a system test after you first install your thermostat. The most common reasons for T errors are that wires are in the wrong thermostat connectors or the wires aren’t fully inserted into the thermostat connectors.

For detailed troubleshooting steps, please see Troubleshooting Nest thermostat T error codes during a System Test.

E error codes 

General information about E errors 

E errors are critical and must be fixed as soon as possible. Your thermostat won’t allow you to control heating or cooling, and the error message won’t go away until the cause has been fixed.

Look at the table below and select your specific error code for troubleshooting help. You can also contact a local Nest Pro.

Caution: It's important to protect you, your system, and your thermostat. Turn off the power to your system at the fuse box before exposing or adjusting any wiring.

1st gen   

          2nd gen         

           3rd gen               

Thermostat E 

E1
E2
E3
E4
E5
E6
E7
E8
E9
E10
E11
E12
E13
E14

E22
E23
E24
E25
E27
E28
E29
E30
E32
E33
E34
E35
E36
E37
E38
E39
E40
E41

E42
E43
E44
E45
E46
E47
E48
E49
E50
E51
E52
E53
E54
E55
E56
E57
E58
E66

E72
E73
E74
E75
E77
E78
E79
E80
E82
E83
E84
E85
E86
E87
E88
E89
E90
E91
E92
E93

E94
E95
E96
E97
E98
E99
E100
E101
E102
E103
E104
E105
E106
E107
E108
E109
E110
E111
E112
E113
E116

E155
E157
E158
E159
E160
E162
E164
E169
E182
E183
E184
E188
E194
E195
E196

 

N error codes

General information about N errors 

N errors aren’t critical and in most cases you can still use your thermostat, but some features may not work, or they won't work as expected, and you’ll see the error in the app. If you're not able to control your heating or cooling with your thermostat, you should try to fix the issue as soon as possible.

Look at the table below and select your specific error code to see if you need to contact a local Nest Pro to help resolve your issue.

Caution: It's important to protect you, your system, and your thermostat. Turn off the power to your system at the fuse box before exposing or adjusting any wiring.

 

   1st gen     

     2nd gen       

       3rd gen         

Thermostat E

N1
N2
N3
N4
N5
N6
N7

N21
N22
N23
N24
N25
N26
N27
N28
N29

N71
N72
N73
N74
N75
N76
N77
N78
N79

N153
N154
N156
N159

 

W error codes

W1
W2
W3
W4
W5

 

M error codes

M12
M13

 

Error code

Troubleshooting

E1

Common wire ("C" wire) is required.

You may need to update your Nest thermostat's software or attach a common wire.

Make sure your thermostat is connected to Wi-Fi.

  1. Press your thermostat's ring to open the Quick View menu.
  2. Select Settings Nest settings icon.
  3. Choose Network.
  4. Your thermostat will take a moment to scan for available networks. Choose your home Wi-Fi network from the list.
  5. Enter your password if prompted. Once connected to Wi-Fi, your thermostat can automatically install updates.

Learn about the common wire and why a Nest thermostat may need one >

   

E2, E22 & E72

No power wires detected. Rc or Rh wire required.

The Nest thermostat isn't physically detecting your Rc or Rhwire or one isn't attached. Or power wires are physically detected, but the Nest thermostat isn't detecting power to the Rc or Rh wire. Either Rc or Rh must be connected for your Nest thermostat to work.

Troubleshoot an E2 error

Troubleshoot an E22 error

Troubleshoot an E72 error

   

E3, E23 & E73

No power to Rc wire detected.

The Nest thermostat isn’t electrically detecting your Rc wire.

These errors can be caused by different things depending on the weather:

   

E4, E24 & E74

No power to Rh wire detected.

The Nest thermostat isn’t electrically detecting your Rh wire.

These errors can be caused by different things depending on the weather:

   

E5, E25, E75 & E155

No heating or cooling detected. W1 or Y1 wire is required.

The Nest thermostat isn't physically detecting your a W1(heating) or Y1 (cooling) wire. One of these wires is required for any type of system that the Nest thermostat supports.

Troubleshoot an E5 error

Troubleshoot an E25 error

Troubleshoot an E75 error

E6

Too many wires detected. Please remove at least one of O/B, W1, Y1 or AUX.

The Nest thermostat doesn't support the configuration of wires you've attached.

Troubleshoot an E6 error

   

E7, E27 & E77

Y1 wire not detected. A heat pump requires a Y1wire.

Your Nest thermostat is physically detecting a wire in the O/Bconnector, which means that you have a heat pump system. Heat pumps require a Y1 wire to be connected.

Troubleshoot an E7 error

Troubleshoot an E27 error

Troubleshoot an E77 error

   

E8, E28 & E78

Additional wire(s) required. W2/AUX detected by itself.

Your Nest thermostat is physically detecting a wire in the W2/AUX connector. Supported configurations that use this connector also include a W1 (heating) wire or an O/B + Y1 wire.

Troubleshoot an E8 error

Troubleshoot an E28 error

Troubleshoot an E78 error

   

E9, E29, E79 & E159

No power to C wire detected.

Your Nest thermostat is physically detecting a wire in the C(common) connector but isn't detecting any power to it.

Troubleshoot an E9 error

Troubleshoot an E29 error

Troubleshoot an E79 error

   

E10, E30, E80 & E160

No power to Y1 wire detected.

Your Nest thermostat is physically detecting a wire in the Y1(cooling) connector but isn't detecting any power to it.

Troubleshooting E10, E30, E80 and E160 error codes

E11

Heat pump wire O/Bdetected. No heat pump system present.

Your Nest thermostat is physically detecting a wire in the O/B(heat pump) connector but isn't detecting any power to it. You may need to update your Nest thermostat's software.

Make sure your thermostat is connected to Wi-Fi.

  1. Press your thermostat's ring to open the Quick View menu.
  2. Select Settings Nest settings icon.
  3. Choose Network.
  4. Your thermostat will take a moment to scan for available networks. Choose your home Wi-Fi network from the list.
  5. Enter your password if prompted. Once connected to Wi-Fi, your thermostat can automatically install updates.
   

E12, E32, E82 & E162

No power to W1 wire detected.

Your Nest thermostat is physically detecting a wire in the W1(heating) connector but isn't detecting any power to it.

  1. Turn off the power to your heating and cooling system at your breaker.
  2. Grip the metal ring of your thermostat and pull it gently towards you away from the wall. Your thermostat should pop right off the base.
  3. Remove the wire in the W1 terminal, straighten it, and put it back in as far as it will go. You may need to strip the end of your wire to make sure enough copper is exposed.
  4. Reattach your thermostat to the baseplate and turn the power back on at your breaker.
  5. If you still see the error message, you should contact a professional to diagnose issues with your heating system.

Contact a Nest Pro >

   

E13, E33 & E83

A heat pump can have at most one auxiliary heat wire.

Your Nest thermostat was previously setup as a single fuel system with auxiliary heat, but it's detecting both W1 and W2/AUX wires. Single fuel heat pump systems support a wire in either W1 or W2/AUX but not in both at the same time.

Troubleshoot an E13 error

Troubleshoot an E33 error

Troubleshoot an E83 error

   

E14, E34, E84 & E164

Dual fuel requires an alternate heat wire.

Your Nest thermostat was previously set up as a dual fuel system, but it's not detecting a W1, W2/AUX or  (W3). One of these wires is required in order to have alternate heat.

Troubleshoot an E14 error

Troubleshoot an E34 error

Troubleshoot an E84 error

 

E35, E85

Dual fuel can have at most two alternate heat wires.

Your Nest thermostat was set up as a dual fuel system, but the W1, W2/AUX and (W3) wires are configured as alternate heat wires.

Troubleshoot an E35 error

Troubleshoot an E85 error

 

E36, E86

A heat pump can have at most one auxiliary heat wire.

Your Nest thermostat was previously set up as a single fuel system with auxiliary heat, but it's detecting W1, W2/AUX and (W3) wires. Single fuel heat pump systems support a wire in only one of these connectors.

Troubleshoot an E36 error

Troubleshoot an E86 error

 

E37, E87

A heat pump can have at most one auxiliary heat wire.

Your Nest thermostat was previously set up as a single fuel system with auxiliary heat, but it's detecting W1 and (W3) wires. Single fuel heat pump systems support a wire in either W1 or (W3) but not in both at the same time.

Troubleshoot an E37 error

Troubleshoot an E87 error

 

E38, E88

A heat pump can have at most one auxiliary heat wire.

Your Nest thermostat was previously set up as a single fuel system with auxiliary heat, but it's detecting W2/AUX and (W3) wires. Single fuel heat pump systems support a wire in either W2/AUX or (W3) but not in both at the same time.

Troubleshoot an E38 error

Troubleshoot an E88 error

 

E39, E89 & E169

Y2 wire without Y1 wire.

Your Nest thermostat is physically detecting a Y2 wire but not a Y1 wire. Both wires are required for 2 stage conventional cooling systems or 2 stage heat pumps.

Troubleshoot an E39 error

Troubleshoot an E89 error

 

E40, E90

W3 wire without W2/AUXwire.

Your Nest thermostat is physically detecting a (W3) wire but not a W2/AUX wire. Both wires are required for 3 stage conventional heating systems.

Troubleshoot an E40 error

Troubleshoot an E90 error

 

E41, E91

E wire without O/B wire.

Your Nest thermostat is physically detecting a (E) wire but not an O/B wire. O/B is a heat pump wire and the Nest thermostat only supports the use of emergency heat with heat pump systems.

Troubleshoot an E41 error

Troubleshoot an E91 error

                                     

E42, E43, E44, E45, E46, E47, E48, E49, E50, E51, E92, E93, E94, E95, E96, E97, E98, E99, E100, E101

Please contact Nest support to help troubleshoot this error.

Your Nest thermostat either has wires that aren't fully inserted into the connectors or has tripped an internal fuse.

Please contact Nest support to help troubleshoot this error.

                         

E52, E53, E54, E55, E56, E57, E58, E102, E103, E104, E105, E106, E107, E108, E182, E183 & E188

The Nest thermostat has an overcurrent error.

There is a problem with the Y1 wire. Your thermostat is not receiving power from your system.

Troubleshoot E52 – E58

Troubleshoot E102 – E108

                         

E66, E116 and E196

No power to Y1 wire detected

Your Nest thermostat may be wired incorrectly, or your system may be incompatible.

Troubleshooting E66, E116, E196, and M13 errors

E109

G2 detected. G1 wire is also required.

Your Nest thermostat is physically detecting a G2 (fan) wire in the Y2 connector, but it’s not detecting a wire in the Gconnector. Both wires are required for a multi-speed fan.

Contact a Nest Pro installer if you need more help.

E110

G2 wire detected. Remove W2/AUX wire.

Your Nest thermostat is physically detecting a wire in the W1connector, a wire in the AUX/W2 connector, and a G2 (fan) wire in the Y2 connector. This indicates you have more than one stage of heat and more than one fan speed.

The Nest thermostat does not support multiple stages of heat and multiple fan speeds at the same time.

Contact a Nest Pro installer if you need more help.

E111

G2 wire detected. Remove E wire.

Your Nest thermostat has detected a G2 (fan) wire in the Y2connector, and an emergency heat wire in the connector. The Nest thermostat doesn’t support a multi-speed fan and emergency heat together.

Contact a Nest Pro installer if you need more help.

E112

G wire detected. G1 and G2also required.

Your Nest thermostat is physically detecting a G3 (fan) wire in the connector, but it isn’t detecting a G2 (fan) wire in the Y2connector or a wire in the G connector. All three wires are required for a three speed fan.

Contact a Nest Pro installer if you need more help.

E113

G2 and O/B wire conflict.

Your Nest thermostat has detected a G2 (fan) wire in the Y2connector, and a wire in the O/B connector. This wiring indicates a multi-speed fan and a heat pump. The Nest thermostat doesn’t support this kind of system.

Contact a Nest Pro installer if you need more help.

E157

Y1 wire not detected.

The Nest thermostat isn't physically detecting your Y1 wire or one isn't attached. A wire in your O/B terminal is configured as a Heat Pump O/B wire. Heat Pumps require a Y1 wire to function.

Take your thermostat display off the wall and check your wires.

Contact a Nest Pro installer if you need more help.

E158

Y1 wire not detected.

The Nest thermostat isn't physically detecting your W1 wire or one isn't attached. A wire in your O/B terminal is configured as a second stage of heat. Your Nest thermostat needs a first stage of heat (W1) to use a second stage of heat.

Take your thermostat display off the wall and check your wires.

Contact a Nest Pro installer if you need more help.

E194

R wire not detected

The Nest thermostat isn't physically detecting your R wire or one isn't attached. An R wire must be connected for your Nest thermostat to work.

Take your thermostat display off the wall and check your wires. Make sure the R wire is fully inserted into the R connector on your Nest Base.

Contact a Nest Pro installer if you need more help.

E195

No power to R wire detected.

The Nest thermostat isn’t electrically detecting your R wire.

  • If it’s summer or there’s a heat wave, read this article first: Troubleshooting during the summer

  • If it’s winter or there’s a cold snap, or if it’s mild weather, follow the instructions below:
    1. Check that the power is on at your breaker.
    2. If there is a wire in your R connector and the power is on but the Nest thermostat isn’t detecting it:
      • Turn the power off at the breaker.
      • Remove your R wire.
      • Straighten or restrip the wire. There should be at least 1 cm of exposed copper.
      • Insert the wire fully into the R connector and make sure the connector button stays pressed down when you let go.
      • Turn the power back on at the breaker.

Contact a Nest Pro installer if you need more help.

 

Error code

Troubleshooting

   

N1, N21 & N71

Power wire Rc detected. Not connected to equipment.

Your Nest thermostat isn't electrically detecting your Rc wire, but one is connected to the Nest thermostat base.

Troubleshoot a N1 error

Troubleshoot a N21 error

Troubleshoot a N71 error

   

N2, N22 & N72

Power wire Rh detected. Not connected to equipment.

Your Nest thermostat isn't electrically detecting your Rh wire, but one is connected to the Nest thermostat base.

Troubleshoot a N2 error

Troubleshoot a N22 error

Troubleshoot a N72 error

   

N3, N23, N73 & N153

No power to W1 wire detected.

Your Nest thermostat isn't electrically detecting your W1 wire, but one is connected to the Nest thermostat base.

Troubleshoot a N3 error

Troubleshoot a N23 error

Troubleshoot a N73 error

   

N4, N24, N74 & N154

No power to Y1 wire detected.

Your Nest thermostat isn't electrically detecting your Y1 wire, but one is connected to the Nest thermostat base.

Troubleshoot a N4 error

Troubleshoot a N24 error

Troubleshoot a N74 error

   

N5, N25 & N75

No power to W2/AUX wire detected.

Your Nest thermostat isn't electrically detecting your W2/AUXwire, but one is connected to the Nest thermostat base.

Troubleshoot a N5 error

Troubleshoot a N25 error

Troubleshoot a N75 error

   

N6, N26, N76 & N156

No power to G wire detected.

Your Nest thermostat isn't electrically detecting your G wire, but one is connected to the Nest thermostat base.

Troubleshoot a N6 error

Troubleshoot a N26 error

Troubleshoot a N76 error

   

N7, N27 & N77

No power to O/B wire detected.

Your Nest thermostat isn't electrically detecting your O/B wire, but one is connected to the Nest thermostat base.

Troubleshoot a N7 error

Troubleshoot a N27 error

Troubleshoot a N77 error

   

N28 & N78

No power to Y2 wire detected.

Your Nest thermostat isn't electrically detecting your Y2 wire, but one is connected to the Nest thermostat base.

Troubleshoot a N28 error

Troubleshoot a N78 error

   

N29, N79 & N159

No power to wire detected.

Your Nest thermostat isn't electrically detecting your wire, but one is connected to the Nest thermostat base.

Troubleshoot a N29 error

Troubleshoot a N79 error

 

W error codes

Error code

Troubleshooting

W1

The Nest thermostat can't continue to connect to your Wi-Fi network.

Your Wi-Fi access point may not fully support a Wi-Fi standard known as power saving mode.

Troubleshoot a W1 error

W2

Failed to connect.

Your Wi-Fi access point may have security settings enabled that prevent your Nest thermostat from connecting.

Troubleshoot a W2 error

W3

Failed to connect.

Your Wi-Fi access point is not providing a network IP address to your Nest thermostat.

Troubleshoot a W3 error

W4

Failed to connect.

The Nest thermostat is connected to your wireless network but not to the Internet.

Troubleshoot a W4 error

W5

Failed to connect.

Your Nest thermostat can't connect to Wi-Fi.

Troubleshoot a W5 error

 

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