Error
number
Description
What’s going on?
E10
E30
No power to Y1wire
detected.
Your Nest is physically detecting a wire in the Y1 connector but isn’t
detecting any power to it.
E11
Heat 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
E33
Heat 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.
E34
Dual 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.
E35
Dual 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.
E36
Heat 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.
E37
Heat 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.
E38
Heat 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.
E39
Y2 wire without Y1wire.
Your Nest is physically detecting a Y2 wire but not a Y1 wire that is
required for 2 stage conventional cooling systems or 2 stage heat
pumps.
E40
W3 wire without W2/AUX
wire.
Your Nest is physically detecting a * (W3) wire but not a W2/AUX wire
that is required for 3 stage conventional heating systems.
E41
E wire without O/B wire.
Your Nest is physically detecting a * (E) wire but not an O/B wire. O/B
is a heat pump wire and Nest only supports the use of emergency
heat with heat pump systems.
Nest Learning Thermostat installation & configuration guide
Page 25
