Navien Tankless Water Heater Error Code 048: How to Fix It

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
048
Brand
Navien
Product Type
water_heater
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code 048 on your Navien tankless water heater indicates a fault with the domestic hot water (DHW) circulator pump. This pump recirculates hot water to reduce wait time at the tap. The error usually means the pump is stuck, failed, or its electrical connections are faulty.
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Tools You'll Need

How to Fix Error Code 048

  1. Turn Off Power and Water

    Electrical hazard. Always disconnect power before servicing.

  2. Access the Circulator Pump

    Be careful of hot surfaces if the unit was recently running. Allow it to cool.

  3. Check for Obstructions

    Do not force the shaft; use gentle pressure.

  4. Inspect Electrical Connections

    Use a multimeter safely. Disconnect power before touching terminals.

  5. Test the Pump Manually

    This step requires electrical knowledge. If unsure, skip to professional help.

  6. Replace the Circulator Pump

    Ensure the unit is properly purged of air to avoid dry firing.

Parts You May Need

DHW circulator pump
Check Price on Amazon
DHW circulator pump
Check Price on Amazon
DHW circulator pump
Check Price on Amazon
DHW circulator pump
Check Price on Amazon
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When to Call a Professional

If you are not comfortable working with electrical components or if the pump replacement does not resolve the error, call a licensed plumber or Navien service technician. The issue may be with the control board or wiring harness.

Frequently Asked Questions

Can I reset error code 048 without fixing anything?
No, error 048 indicates a hardware fault. Resetting the unit (turning power off/on) may clear the code temporarily, but it will return if the pump issue persists. You must diagnose and fix the pump.
How much does it cost to replace a Navien circulator pump?
The pump part costs around $100–$250, and professional installation adds $100–$200. DIY replacement can save labor costs.
Will error 048 damage my water heater?
Yes, if the pump is not working, the unit may overheat or fail to deliver hot water. Continued operation may damage the heat exchanger. Address promptly.
Is error 048 covered under warranty?
Navien warranties typically cover defective parts for a limited time (e.g., 5-15 years). If your unit is under warranty, contact Navien for a free replacement pump.
Do I need to drain the unit to replace the pump?
Yes, you should drain the water heater to avoid flooding and to safely remove the pump. Refer to your manual for drain procedure.

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