Ecobee Thermostat Not Working?
Fix blank screens, PEK wiring issues, SmartSensor pairing failures, touchscreen problems, and HVAC alerts on all Ecobee models. No battery to charge — power issues point straight to wiring.
Last updated: February 2026
Safety Warning
Always turn off the HVAC breaker before removing your Ecobee from its wall plate or touching any wires. The thermostat runs on low-voltage 24V, but the furnace and air handler connections carry dangerous 120V/240V power.
Common Ecobee Problems & Quick Fixes
Blank/black screen
No internal battery. Check breaker, furnace switch, and PEK wiring at the furnace.
Stuck on "Calibrating"
Wait 15 min after install. If stuck, pull off plate, wait 30 sec, reattach.
"Furnace running too long" alert
Check air filter, insulation, and set temperature. Adjust alert threshold in Settings.
SmartSensor not responding
Replace CR2032 battery. Re-pair: Sensors > Add Sensor. Check range (45 ft max).
Touchscreen unresponsive
Clean screen with dry cloth. Restart by pulling off wall plate. Check for firmware update.
Won't connect to Wi-Fi
Use 2.4GHz network. Re-enter password. Check router channel for congestion.
8-Step Ecobee Troubleshooting Guide
Check the display and power status
Tap the Ecobee touchscreen to wake it. If the screen is completely blank, the thermostat has no power — Ecobee units don't have an internal rechargeable battery like Nest. Pull the thermostat off the wall plate and check if the green LED on the back plate is lit (indicates 24V power is present). If the LED is off, the issue is with your HVAC power supply, wiring, or PEK installation. If the LED is on but the screen is black, the thermostat itself may be faulty.
Check the circuit breaker and furnace power
Find the HVAC breaker in your electrical panel and confirm it's in the ON position. Also look for a power switch on or near your furnace — it resembles a standard light switch and is sometimes accidentally flipped off. Check for a blown 3-amp or 5-amp fuse on the furnace control board (common on older systems). If the breaker keeps tripping, you likely have a short in the HVAC wiring or transformer — call an HVAC technician.
Inspect the wiring and PEK installation
Turn off the HVAC breaker before touching any wires. Pull the Ecobee off the wall plate and photograph the wiring. Verify each wire is fully inserted into the correct terminal — push firmly until it clicks. Key terminals: Rc (red, cooling power), Rh (red, heating power), W (white, heat), Y (yellow, cooling), G (green, fan), and C (blue, common). If you don't have a C wire and used the PEK, open your furnace panel and verify the PEK wiring matches the diagram that came with your Ecobee. A loose PEK connection is one of the most common causes of Ecobee power issues.
Check for alerts and error messages
Swipe right on the Ecobee home screen or go to Main Menu > Alerts to view current alerts. Common ones: "Furnace running too long" — your system ran past the safety limit without reaching the set temperature (check filter, sizing, insulation). "AC running too long" — similar issue for cooling. "Low humidity" or "High humidity" — humidifier/dehumidifier issue. "Sensor not responding" — a SmartSensor has lost connection (check battery). "Equipment malfunction" — an HVAC component failed to respond. Note the exact alert text for further troubleshooting.
Test your HVAC equipment
Go to Main Menu > Settings > Installation Settings > Equipment > Wiring. The Ecobee shows which wires it detects. If a wire is connected but not detected, it may be loose or broken. Next, manually test your system: set the thermostat to Heat mode and raise the temperature 5 degrees above the current reading. Listen for the furnace to kick on within 30 seconds to 2 minutes. If nothing happens, switch to Cool mode and lower the temperature 5 degrees to test AC. If neither responds, the issue is wiring or equipment, not the thermostat.
Restart the Ecobee thermostat
Pull the thermostat off the wall plate, wait 30 seconds, then push it back on firmly. This forces a complete power cycle. Alternatively, go to Main Menu > Settings > Reset > Restart. Unlike a factory reset, a simple restart preserves all your settings, schedules, and sensor pairings. If the thermostat is frozen or the touchscreen is unresponsive, removing it from the wall plate is the only way to force a restart.
Check Wi-Fi connection and update firmware
Go to Main Menu > Settings > Wi-Fi and verify you're connected with a strong signal. If disconnected, select your network and re-enter the password. Ecobee primarily uses 2.4GHz — if your router combines 2.4GHz and 5GHz under one SSID, the thermostat may struggle to connect. Then check Main Menu > About to see your current firmware version. Firmware updates are pushed automatically over Wi-Fi, but connectivity issues can delay them. Outdated firmware can cause touchscreen lag, sensor pairing failures, and HVAC control issues.
Factory reset as a last resort
Go to Main Menu > Settings > Reset > Reset All. This erases everything: Wi-Fi credentials, schedules, SmartSensor pairings, comfort settings, and preferences. After reset, the Ecobee will boot into the initial setup wizard. You'll need to re-pair all SmartSensors, reconnect to Wi-Fi, and reconfigure your schedule. If problems persist after a factory reset, the thermostat hardware is likely defective — contact Ecobee support. Ecobee offers a 3-year warranty from the date of purchase.
If these steps resolved your issue, your thermostat should now be working correctly.
Pro Tip
Unlike Nest thermostats, Ecobee units have no rechargeable battery — they depend entirely on your HVAC system's 24V transformer for power. This means a blank screen always indicates a wiring or power supply problem, never a "dead battery." Check the green LED on the back plate: if it's lit, power is reaching the plate and the thermostat itself may be faulty. If it's off, trace the issue back to your breaker, furnace fuse, or PEK wiring.
The PEK (Power Extender Kit) — Ecobee's C Wire Solution
Every Ecobee thermostat ships with a Power Extender Kit (PEK) in the box. The PEK is designed for homes that don't have a C (common) wire — it installs at your furnace or air handler and repurposes an existing wire to deliver continuous 24V power to the thermostat. While the PEK works well when installed correctly, it's also one of the most common sources of Ecobee problems:
- Blank screen or random power loss (PEK wire came loose at furnace)
- Thermostat powers on but HVAC won't start (PEK wired to wrong terminals)
- Heating works but cooling doesn't, or vice versa (PEK configuration mismatch)
- Intermittent shutoffs during high-demand cycles (PEK connection corroded or loose)
- System short-cycling on and off rapidly (PEK installed on incompatible system)
How to verify your PEK installation:
Check the PEK wiring at the furnace
EasyTurn off the breaker. Open the furnace panel and locate the PEK module (small green circuit board). Verify each wire matches the wiring diagram from your Ecobee installation. Ensure all wires are firmly seated in the PEK terminals.
Bypass the PEK with a direct C wire
MediumIf you have an unused wire in your thermostat cable, connect it directly from the C terminal on the furnace control board to the C terminal on the Ecobee wall plate. Remove the PEK entirely. This is the most reliable long-term solution.
Run a new thermostat cable
HardIf your existing cable doesn't have a spare wire, run a new 5-wire (18/5) thermostat cable from the furnace to the thermostat location. This eliminates the need for the PEK entirely and supports all HVAC functions.
Related Ecobee Guides
Frequently Asked Questions
Written by
ThermostatFixer Editorial Team
Our team of HVAC enthusiasts and DIY experts creates detailed thermostat troubleshooting guides, wiring diagrams, and repair tips to help homeowners fix common thermostat issues without calling a technician.