Google Nest Thermostat Error Code E186: How to Fix It

Easy 10-20 minutes Medium Severity Verified June 2026
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Error Code
E186
Brand
Google Nest
Product Type
thermostat
Severity
Medium
DIY Difficulty
Easy
Estimated Fix Time
10-20 minutes
Error E186 on your Google Nest Thermostat indicates a humidity sensor fault. This usually means the internal sensor is not reading correctly, which can affect your system's comfort settings. Follow these steps to troubleshoot and resolve the issue.
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Tools You'll Need

How to Fix Error Code E186

  1. Restart Your Nest Thermostat

  2. Check for Software Updates

    Ensure your thermostat is connected to Wi-Fi during the update.

  3. Clean the Sensor Area

    Do not use any liquids or cleaners.

  4. Reset the Humidity Sensor Settings

    Resetting will delete any custom sensor calibrations.

  5. Perform a Factory Reset (if needed)

    A factory reset removes all schedules, preferences, and equipment configurations. Take note of your wiring before resetting.
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When to Call a Professional

If the error still appears after a factory reset, the humidity sensor may be physically damaged. Contact Google Nest Support or a professional HVAC technician to replace the thermostat.

Frequently Asked Questions

What does error E186 mean on a Nest Thermostat?
It indicates a humidity sensor fault, meaning the thermostat's internal sensor is not functioning correctly, potentially causing inaccurate humidity readings.
Can I ignore E186 error on my Nest?
It's not recommended. The error may cause your HVAC system to run inefficiently, affecting comfort and energy usage. Resolve it promptly.
How do I reset the humidity sensor on my Nest Thermostat?
Go to Settings > Equipment > Reset > Sensor, then select 'Humidity Sensor' and confirm the reset.
Will a power cycle fix Nest error E186?
Yes, a soft restart (holding the ring for 10 seconds) often resolves temporary sensor glitches.
Is a humidity sensor fault covered under warranty?
Google Nest thermostats typically have a 2-year limited warranty. If the sensor is defective, contact support for a replacement.

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