E021
Navien Air Pressure Switch / Fan Failure

Unit shows E021 and will not operate; often associated with fan or air pressure issues.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Faulty air pressure switch, Blocked intake or exhaust vent, Failed combustion fan motor, Disconnected or cracked air pressure tubing

How to Fix / Troubleshooting

Safety: Turn OFF power before removing the cover. Do not run the unit with the cover removed.

Steps:

  • 1. Inspect venting: Check both intake and exhaust terminations outside for obstructions (ice, snow, debris). Ensure vent pipes are not sagging or filled with condensate.
  • 2. Check condensate drain: Make sure the condensate trap and drain line are not clogged or frozen, as backed-up condensate can restrict airflow.
  • 3. Inspect air pressure tubing: Inside the unit, locate the small silicone tubes running from the fan housing to the air pressure switch. Ensure they are firmly connected, not kinked, and not cracked.
  • 4. Listen for fan operation: With the cover back on, restore power and call for hot water. Listen for the combustion fan starting. If the fan does not run or makes grinding noises, it may be failing.

If E021 remains after clearing vents and checking tubing, the air pressure switch or fan motor likely needs replacement by a qualified technician.

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Repair Difficulty

Hard 4/5

Required Part

Air Pressure Switch
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