Exact model-family answer directory
ecobee3 lite troubleshooting
ecobee3 lite (EB-STATE3LT*): electrical and wiring (from the ecobee3 lite manual and ecobee); compatibility; wi-Fi, and a fix for each symptom below.
- Electrical and wiring (from the ecobee3 lite manual and ecobee)24 VAC, 3.5 VA, with 18 to 22 gauge wire. It needs a C wire for continuous power, or the Power Extender Kit, which combines the Y and G functions onto one wire so the freed wire can be the C.
Confirm the model first
Which units this covers, and how to tell yours is one of them
- Model numbers and patterns
- EB-STATE3LT*
Published specification
What is true of this model and changes how you fix it
- Device — value smart THERMOSTATThe value ecobee thermostat. Crucially it does NOT include a room sensor in the box and has NO built-in occupancy/proximity sensor like the higher ecobee models — so occupancy-based features (Smart Home/Away using the thermostat's own presence) are limited; it can use add-on SmartSensors (sold separately) for room temperature/occupancy.
- Wiring — C-wire / PEKFor reliable power it needs a common (C) wire, or the included Power Extender Kit (PEK) if you have no C-wire — a thermostat that reboots, loses Wi-Fi or won't power on is very often a missing/incorrect C-wire. Confirm the wiring during install.
- App & platformManaged in the ecobee app with scheduling and geofencing; works with major smart-home platforms. Some advanced sensors/features are reserved for the higher ecobee models.
- CompatibilityMost 24 VAC systems: furnaces, ACs (2H/2C), heat pumps (2H/2C plus 2 stage aux), boilers, PTACs and fan coils with 3 speeds. Millivolt, high-voltage, dual-transformer and communicating systems are not compatible with the Power Extender Kit.
- Wi-Fi2.4 GHz only. It does not support 5 GHz.
Where these figures were read. ecobee.com/en-us/smart-thermostats/smart-thermostat-lite/ (renamed from ecobee3 lite to Smart Thermostat Lite) (value smart thermostat, no included room sensor/occupancy)
Manufacturer support for this product line. Ecobee Support — Thermostat support. Official ecobee thermostat, sensor, HVAC and account support.
Also read for this model. ecobee Support — ecobee smart thermostat upgrade guide; ecobee — Power Extender Kit.
Exact questions
Questions that only have an answer for the ecobee3 lite
My ecobee3 lite keeps losing Wi-Fi or rebooting.+
That is almost always a power/wiring issue — the ecobee needs steady power, which comes from a common (C) wire. If you have no C-wire, the included Power Extender Kit (PEK) must be installed at the furnace/air handler to supply it; without a C-wire or PEK, the thermostat 'power-steals' and can reboot, drop Wi-Fi or misbehave, especially with certain HVAC systems. Verify the C-wire or PEK is correctly wired. Unlike the higher ecobee models, the 3 lite also has no built-in occupancy sensor, so presence-based features are limited unless you add SmartSensors.