Lennox HVAC Error Code E25: How to Fix It

Easy 30 minutes to 1 hour Medium Severity Verified June 2026
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Error Code
E25
Brand
Lennox
Product Type
hvac
Severity
Medium
DIY Difficulty
Easy
Estimated Fix Time
30 minutes to 1 hour
Lennox error code E25 on your HVAC system indicates a condensate pump fault. This means the pump that removes water from your air conditioner or furnace is not working properly, often due to a clog, float switch issue, or pump failure. Follow these steps to troubleshoot and resolve the problem.
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Tools You'll Need

How to Fix Error Code E25

  1. Turn Off Power to the System

    Always turn off power before servicing electrical components.

  2. Locate the Condensate Pump

  3. Check for Clogs in the Drain Lines

    Be careful not to spill water on electrical parts.

  4. Test the Condensate Pump Operation

    Do not overfill; use enough water to trigger the float.

  5. Check the Float Switch

  6. Inspect the Check Valve (if present)

  7. Reset the System

  8. Replace the Condensate Pump if Needed

    If you're uncomfortable with electrical work, call a technician.

Parts You May Need

Condensate pump
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Check valve
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Condensate pump
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Check valve
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Condensate pump
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Check valve
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Condensate pump
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Check valve
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When to Call a Professional

If you've cleaned the drain lines and the pump doesn't work after testing, or if you're not comfortable working with electrical components, call a professional HVAC technician. Also, if the error persists after replacing the pump, there may be a control board issue.

Frequently Asked Questions

What does Lennox error code E25 mean?
Error code E25 indicates a condensate pump fault. The system has detected that the pump is not removing water properly, often due to a clog or pump failure.
Can I bypass the condensate pump to clear error E25?
No, bypassing the pump is not recommended. The pump is essential for removing moisture; bypassing it can cause water damage. Instead, fix the pump or call a professional.
How do I reset Lennox error code E25?
First, fix the underlying pump issue. Then, turn off power to the system for 30 seconds and restore it. If the pump is working, the error should clear automatically.
Is it safe to run my Lennox HVAC with error E25?
No, running the system with a condensate pump fault can lead to water overflow and damage. Shut off the system until the issue is resolved.
How do I clean the condensate pump float switch?
Remove the pump cover and gently clean the float with a brush or cloth to remove any debris. Ensure it moves up and down freely.

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