Lennox HVAC Error Code E26: How to Fix Humidity Sensor Fault

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
E26
Brand
Lennox
Product Type
hvac
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code E26 on your Lennox HVAC system indicates a humidity sensor fault. This sensor monitors indoor humidity levels to optimize comfort and efficiency. When it fails, your system may not dehumidify properly, leading to discomfort or reduced efficiency. Follow these steps to diagnose and fix the issue.
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Tools You'll Need

How to Fix Error Code E26

  1. Power Down the System

    Always shut off power before servicing electrical components to avoid shock.

  2. Locate the Humidity Sensor

  3. Check Sensor Connections

  4. Clean the Sensor

    Do not wet the sensor as moisture can damage it.

  5. Test Sensor Continuity

  6. Replace the Sensor if Faulty

    Ensure replacement sensor matches your model (check part number on old sensor or manual).

  7. Restore Power and Test

Parts You May Need

Humidity Sensor Replacement
Check Price on Amazon
Humidity Sensor Replacement
Check Price on Amazon
Humidity Sensor Replacement
Check Price on Amazon
Humidity Sensor Replacement
Check Price on Amazon
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When to Call a Professional

If cleaning and replacing the sensor does not clear the error code, or if you are uncomfortable working with electrical components, contact a licensed HVAC technician. The issue may be with the control board or wiring harness.

Frequently Asked Questions

What does Lennox error code E26 mean?
Error code E26 indicates a humidity sensor fault in your Lennox HVAC system.
Can I run my HVAC with error code E26?
The system may still operate, but dehumidification may be impaired. It's best to fix the issue promptly to maintain comfort and efficiency.
How much does it cost to replace a humidity sensor on a Lennox system?
The part typically costs $20-$60, and professional installation may add $100-$200. DIY replacement can save on labor.
Where is the humidity sensor located on a Lennox HVAC?
It is usually mounted on the return air duct near the air handler or furnace, often inside a small plastic enclosure.
How do I test a Lennox humidity sensor?
Use a multimeter set to continuity. Disconnect the sensor and check across its terminals. No continuity indicates a faulty sensor.

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