What is the Ecobee PEK (Power Extender Kit) and when do I need it?

The PEK (Power Extender Kit) is a small relay module that comes free with every Ecobee thermostat. You need it when your existing wiring doesn't include a C (common) wire. The PEK installs at your furnace or air handler and repurposes an existing wire (typically the fan/G wire) to provide continuous 24V power to the Ecobee. Without the PEK or a dedicated C wire, the Ecobee will not power on at all — unlike Nest, it cannot trickle-charge through HVAC calls.

How do I re-pair an Ecobee SmartSensor that stopped reporting?

First, pull the SmartSensor off its stand and replace the CR2032 battery (battery lasts about 18 months). After inserting the new battery, wait 2 minutes for the sensor to boot. On your Ecobee, go to Main Menu > Settings > Sensors > Add Sensor. The thermostat will search for nearby sensors. If it doesn't appear, hold the sensor within 5 feet of the thermostat during pairing. If pairing still fails, remove the sensor from the app first (Settings > Sensors > select sensor > Delete), then re-add it.

Why does my Ecobee show "Furnace running too long" alert?

This alert means your heating system ran continuously beyond the runtime threshold (default is 2.5 hours for most systems). Common causes: (1) undersized furnace for your home, (2) extremely cold weather pushing the system beyond capacity, (3) poor insulation or air leaks, (4) dirty air filter restricting airflow. To adjust the threshold, go to Main Menu > Settings > Thresholds > Furnace Max Runtime. If the alert appears during moderate weather, have an HVAC technician check your system sizing and ductwork.

Can I fix an Ecobee touchscreen that is unresponsive or glitchy?

Yes, in most cases. First, try a reboot by pressing and holding the power button on the thermostat for 10 seconds, or pull it off the wall plate and reattach it. If the touchscreen responds to some areas but not others, perform a screen recalibration from Main Menu > Settings > About > Recalibrate Screen. Clean the screen with a dry microfiber cloth — moisture or cleaning products can cause ghost touches. If only part of the screen works after calibration, the digitizer is likely damaged and the unit needs replacement.

Why does my Ecobee keep losing Wi-Fi connection?

Ecobee thermostats use 2.4GHz Wi-Fi only. Common Wi-Fi fixes: (1) ensure your router's 2.4GHz band is enabled and not set to auto-disable, (2) check that your Ecobee is within range — thick walls or metal HVAC equipment nearby can weaken the signal, (3) update your Ecobee firmware at Main Menu > Settings > About > Check for Updates, (4) if your router uses band steering, it may force the Ecobee to 5GHz — create a separate 2.4GHz SSID. Also verify the Ecobee has stable power — low PEK voltage can cause intermittent connectivity.

How do I fix humidity control issues on my Ecobee?

Ecobee can control humidifiers and dehumidifiers if wired to the ACC+/ACC- terminals. If humidity readings seem off, note that the built-in sensor measures humidity at the thermostat location, which may differ from the rest of the house. To calibrate: go to Main Menu > Settings > Installation Settings > Thresholds and adjust the humidity setpoints. If you have a whole-home humidifier connected but it's not activating, verify the accessory wiring at Main Menu > Settings > Installation Settings > Equipment > Humidifier. The Ecobee also offers a "Frost Control" feature that automatically lowers humidity targets in cold weather to prevent window condensation.

Repair Guide

Fixing Your Ecobee Thermostat

A comprehensive repair guide for PEK issues, SmartSensor problems, touchscreen fixes, wiring errors, equipment alerts, and humidity control on all Ecobee models.

Last updated: February 2026

Safety Warning

Turn off your HVAC breaker before working on any wiring. While thermostat wires are low-voltage (24V), the furnace and breaker connections carry dangerous 120V/240V. Never work on wiring with the power on.

Quick Diagnosis: What's Wrong With Your Ecobee?

Won't power on

Root cause: PEK wiring fault or blown furnace fuse

Fix: Reseat PEK wires + check fuse

See step 2

SmartSensor not responding

Root cause: Dead CR2032 battery or out of range

Fix: Replace battery + re-pair sensor

See step 4

"Furnace running too long"

Root cause: Runtime exceeds threshold (2.5 hrs default)

Fix: Adjust threshold or check equipment

See step 6

Touchscreen unresponsive

Root cause: Software glitch or digitizer damage

Fix: Reboot + recalibrate screen

See step 5

Incorrect humidity reading

Root cause: Sensor placement or accessory wiring

Fix: Calibrate + check ACC terminals

See step 7

Wi-Fi keeps disconnecting

Root cause: 2.4GHz band issue or low PEK voltage

Fix: Separate 2.4GHz SSID + check PEK

See step 2, 5

8-Step Ecobee Repair Guide

Diagnose the specific problem

Start by identifying the exact issue on your Ecobee. Go to Main Menu > Settings > About to check firmware version and device info. Then check Main Menu > Settings > Installation Settings > Equipment to verify all equipment is detected. Look at the home screen — a flame icon means heating is active, a snowflake means cooling. If you see a "Calibrating" message, wait 5 minutes for it to stabilize. Check Main Menu > Settings > Thresholds for any triggered alerts. Also open the Ecobee app on your phone — go to Settings > Alerts & Reminders for any active warnings like "Furnace running too long" or "Temperature not reached."

Fix PEK (Power Extender Kit) issues

If your Ecobee won't power on or frequently reboots, the PEK may be incorrectly installed. Turn off the HVAC breaker. At the furnace, locate the PEK module — it should be mounted near the control board. Verify all 5 wires are securely inserted: R (24V hot), C (common), G (fan), Y (cooling), and W (heating). The PEK repurposes the G wire to provide C wire power, so the fan is controlled through the PEK relay instead. If any wire is loose, press the terminal tab and reseat it. After verifying connections, check that the PEK's LED blinks green when the breaker is turned back on. A solid red LED means the PEK isn't receiving 24V — check the furnace transformer and fuse (usually a 3A or 5A automotive-style fuse on the control board).

Fix wiring problems

Turn off the HVAC breaker. Pull the Ecobee off its wall plate by grasping the bottom and pulling straight out. Check each wire connection — the Ecobee uses spring-loaded terminals, so press the tab next to each terminal and verify the wire is fully inserted with bare copper visible. Common Ecobee wiring issues: (1) Rc vs Rh confusion — if you have a single R wire, insert it into Rc and leave the Rc/Rh jumper in "auto" mode (the Ecobee handles this internally). (2) Two-transformer systems — if you have separate heating and cooling transformers, connect Rh for heating power and Rc for cooling power. (3) O/B wire — heat pump systems need the O/B wire; verify it's set to "O" (Energize on Cool, standard for most heat pumps) or "B" (Energize on Heat, used by Rheem/Ruud). Configure at Main Menu > Settings > Installation Settings > Equipment > Heat Pump.

Fix SmartSensor issues

If SmartSensors show "Not Responding": (1) Replace the CR2032 coin cell battery — pry off the sensor back cover with a coin or fingernail. Battery life is approximately 18 months. (2) After replacing the battery, wait 2 minutes, then check if the sensor reconnects automatically. (3) If it doesn't reconnect, delete the sensor from Main Menu > Settings > Sensors > select sensor > Delete, then re-add it with Add Sensor. (4) SmartSensors use 915MHz RF (not Wi-Fi), with a range of about 45 feet line-of-sight. If the sensor is behind thick walls or on a different floor, move it closer. (5) If you have more than 32 sensors paired (the maximum), you'll need to remove unused ones before adding new ones. (6) For occupancy detection issues, ensure the sensor isn't placed where pets frequently pass — it cannot distinguish between human and pet motion.

Fix touchscreen and display issues

If the Ecobee touchscreen is unresponsive or registers incorrect touches: (1) Remove the thermostat from the wall plate and reattach it — this performs a soft reboot. (2) Clean the screen with a dry microfiber cloth only — never use water, Windex, or cleaning products on the touchscreen as moisture can damage the digitizer. (3) Perform screen recalibration at Main Menu > Settings > About > Recalibrate Screen — follow the on-screen prompts to tap each target precisely. (4) If the screen flickers or shows artifacts, check for loose ribbon cable connections — pull the unit off the wall plate and inspect the back for any visible damage. (5) For the Ecobee Premium with built-in Alexa, a frozen screen may be caused by a voice processing hang — hold the power button for 10 seconds to force restart. If the screen has permanent dead zones after calibration, the hardware needs replacement.

Fix equipment runtime alerts and threshold settings

The "Furnace running too long" and "AC running too long" alerts are triggered when equipment exceeds the configured runtime threshold. To adjust: Main Menu > Settings > Thresholds > set "Furnace Max Runtime" (default 2.5 hrs for stage 1, 4 hrs for stage 2) and "AC Max Runtime" (default 4 hrs for stage 1). If these alerts trigger during extreme weather, increase the thresholds by 30-60 minutes. If they trigger during moderate weather, the system may be undersized or have issues — check for dirty filters, blocked vents, refrigerant leaks (AC), or failed ignitor (furnace). The "Temperature not reached" alert means the system ran its full cycle without hitting the setpoint — this also points to equipment performance or sizing problems. Go to Main Menu > Home IQ > System Monitor to review runtime patterns.

Fix humidity and comfort issues

If your Ecobee shows incorrect humidity: the built-in humidity sensor can read 5-10% differently from standalone hygrometers due to placement near the wall. For whole-home humidifier or dehumidifier control, wire the accessory to the ACC+/ACC- terminals and configure at Main Menu > Settings > Installation Settings > Equipment > Humidifier/Dehumidifier. Set the "Humidity Setpoint" under Main Menu > Settings > Comfort Settings. Enable "Frost Control" if you see window condensation in winter — this automatically lowers the humidity target based on outdoor temperature. If the Ecobee over-humidifies, increase the "AC Overcool Max" setting (Main Menu > Settings > Thresholds) so the AC can run slightly past the cooling setpoint to remove moisture. For ventilator control, use the ACC terminals and set a minimum runtime per hour.

Factory reset and re-setup

If all else fails: Main Menu > Settings > Reset > Reset All. This erases all settings, schedules, and sensor pairings — your Ecobee will restart the initial setup wizard. Have your Wi-Fi password ready, and know your HVAC system type (conventional, heat pump, dual fuel). During setup, the Ecobee will detect wiring automatically and configure equipment. You'll need to re-pair all SmartSensors after a reset. If your Ecobee still has issues after factory reset, check for firmware updates immediately at Main Menu > Settings > About > Check for Updates. If problems persist, contact Ecobee support at ecobee.com/support — Ecobee offers a 3-year warranty from the date of purchase, which is longer than most competitors.

If these steps resolved your issue, your thermostat should now be working correctly.

Pro Tip

Before installing the PEK, check if you have an unused wire in your thermostat cable. If there's a blue or brown wire not connected to any terminal, you can use it as a dedicated C wire instead of the PEK. Connect it to the C terminal on both the Ecobee wall plate and your furnace control board. A direct C wire is more reliable than the PEK since it eliminates the relay as a potential failure point.

Ecobee Alert & Error Reference

Alert	Meaning	Fix
Furnace running too long	Heating exceeded max runtime threshold	Check filter, vents, insulation. Adjust threshold in Settings > Thresholds
AC running too long	Cooling exceeded max runtime threshold	Check refrigerant, coils, outdoor unit. Increase threshold if extreme weather
Temperature not reached	System ran full cycle without hitting setpoint	Check equipment sizing, ductwork leaks, and filter condition
Sensor not responding	SmartSensor lost connection for 30+ minutes	Replace CR2032 battery. Re-pair sensor if needed
Low battery (sensor)	SmartSensor CR2032 is depleted	Replace with new CR2032. Battery lasts ~18 months
PEK not detected	Power Extender Kit lost connection	Reseat PEK wires at furnace. Check furnace fuse and transformer
Auxiliary heat running	Heat pump aux/emergency heat activated	Normal in cold weather. If frequent in mild temps, check heat pump refrigerant
Filter reminder	Scheduled filter change based on runtime hours	Replace air filter. Reset reminder in Settings > Reminders

When to Replace Your Ecobee

Replace rather than repair if:

Touchscreen has permanent dead zones or cracks that persist after recalibration
The unit randomly reboots even with stable PEK or C wire power supply
Built-in microphone or speaker on Ecobee Premium is damaged (voice control and intercom rely on these)
Factory reset doesn't resolve persistent freezing, error alerts, or connectivity issues
Your model is Ecobee3 (original) or older and no longer receives firmware updates or app support
The wall plate terminals show burn marks, corrosion, or melted plastic from a wiring short

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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.