Nest thermostat error codes

Error numberDescriptionWhat’s going on?
E1Common wire C required.This wiring error may appear after installation when Nest can’t get power while the system is turned on. Nest’s software should be updated if this error appears
E2 E22No power wires detected. Rh or Rc wire is required.You’ll see this error when either a Rh or Rc wire was not installed or the Rh or Rc wire that was installed isn’t powered.
E3 E23No power to Rewire detected.You’ll see this error if you’ve installed both an Rc wire and Nest isn’t electrically detecting it.
E4 E24No power to Rh wire detectedYou’ll see this error if you’ve installed both an Rh wire and Nest isn’t electrically detecting it
E5 E25No heating or cooling wires detected.Nest cannot detect any wires inserted into W1 or Y1. At least one of these is required.
W1 or Y1 wire is required
E6Too many wires detected.This error indicates that the wiring combination you’ve installed is no supported by Nest. Verify the actual wiring for the system and remove at least one of 0/B, W1, Y1 or AUX wires as appropriate.
E7 E27Y1 wire not detected. Heat pump requires a Y1 wire.Your Nest is physically detecting a wire in the 0/B connector. This connector is exclusively used for heat pumps which also require a Y1 wire to be attached.
E8 E28Additional wire(s)l required. AUX/W2 detected by itself.Your Nest is physically detecting a wire in the AUX/W2 connector. Supported configurations that use this connector also include a W1 wire or an 0/B + Y1 wire.
E9 E29No power to C wire detected.Your Nest is physically detecting a wire in the C connector, but isn’t detecting any power to it.
E10 E30No power to Y1 wire detected.Your Nest is physically detecting a wire in the Y1 connector but isn’t detecting any power to it.
E11Heat pump wireO/B detected. No heat pump system present.Your Nest is physically detecting a wire in the O/B connector but isn’t detecting any power to it.
You may need to update your Nest’s software.
E13 E33Heat pump can have at most one auxiliary heat wire.Your Nest was previously setup as a single fuel system with auxiliary heat put it’s detecting both W1 and AUX/W2 wires that aren’t supported in that configuration.
E34Dual fuel requires an alternate heat wire.Your Nest was previously setup as a dual fuel system but it’s not detecting a W1, AUX/W2 or * (W3) wire that is required to have alternate heat.
E35Dual fuel can have at most two alternate heat wires.Your Nest was setup as a dual fuel system, but the W1, AUX/W2 and * (W3) wires are configured as alternate heat wires.
E36Heat pump can have at most one auxiliary heat wire.Your Nest was previously setup as a single fuel system with auxiliary heat, but it’s detecting W1, AUX/W2 and * (W3) wires that aren’t supported in that configuration.
E37Heat pump can have at most one auxiliary heat wire.Your Nest was previously setup as a single fuel system with auxiliary heat, but it’s detecting W1 and * (W3) wires that aren’t supported in that configuration.
E38Heat pump can have at most one auxiliary heat wire.Your Nest was previously setup as a single fuel system with auxiliary heat, but it’s detecting AUX/W2 and * (W3) wires that aren’t supported in that configuration.
E42 E51Your Nest may have tripped an internal fuse and Nest needs to be replaced.Your Nest either has wires that aren't fully inserted into the connectors or has tripped an internal fuse.
N1 N21Power wire Rc detected. Not connected to equipment.Your Nest isn’t electrically detecting your Rc wire, but one is connected to the Nest base.
N2 N22Power wire Rh detected. Not connected to equipment.Your Nest isn’t electrically detecting your Rh wire, but one is connected to the Nest base.
N3 N23No power to Wlwire detected.Your Nest isn’t electrically detecting your W1 wire, but one is connected to the Nest base.
N4 N24No power to Y1 wire detected.Your Nest isn’t electrically detecting your Y1 wire, but one is connected to the Nest base.
N5 N25No power to AUX/W2 wire detected.Your Nest isn’t electrically detecting your AUX/W2 wire, but one is connected to the Nest base.
N6 N26No power to G wire detected.Your Nest isn’t electrically detecting your G wire, but one is connected to the Nest base.
N7 N27No power to 0/B wire detected.Your Nest isn’t electrically detecting your 0/B wire, but one is connected to the Nest base.
W2Failed to connect.Your Wi-Fi access point may have security settings enabled that prevent your Nest from connecting.
W3Failed to connect.Your Wi-Fi access point is not providing a network IP address to your Nest.
W4Failed to connect.Nest is connected to your wireless network but not to the internet.