My ecobee is not powering up after installation. What could be the reason?

This article applies to all ecobee thermostats except Smart, Smart SI, EMS and EMS SI.


Incorrect wiring:

  • Check to make sure that your R/RC/RH wire is connected to the RC terminal

  • Check that all wires are properly inserted into the terminal blocks on the ecobee by giving the wires a gentle tug to ensure they’re securely connected

  • If you’ve installed the PEK with the ecobee3 lite or ecobee4, verify the wiring at your ecobee looks as follows:

    • R wire >> RC terminal
    • G wire >> C terminal
    • W wire >> W1 terminal
    • Y wire >> PEK terminal

  • Check the wiring on the furnace control board to ensure that your C wire is connected to the C terminal. If you’ve installed the PEK, the C wire coming off the PEK must be connected to the C terminal on the board


Insufficient voltage:

If you’ve verified that the wiring is correct, then there’s a good chance the issue is voltage-related. You can check the voltage yourself if you have a voltmeter; test for voltage between the RC and C wires at the ecobee—anything less than 24VAC will not power the ecobee.

  • Ensure that the power is turned on from the circuit breaker

  • Some furnaces have a safety switch that cuts off power to the equipment if the equipment cover panel is not closed properly. Please ensure the cover panel of the furnace is closed properly

  • Inspect the fuse on the actual furnace control board (typically a 3 or 5 amp fuse). A blown fuse will need to be replaced

  • If you’re not using the PEK, a short in the C wire could also be an issue (often accompanied by a clicking sound at the thermostat). Try either installing the PEK or re-purposing one of your wires as a C. If the ecobee powers on, there must be an issue with the C wire itself


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