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Navien · Tankless water heater

E109 Fan motor abnormal

High severity Navien NPE-2

What the control is telling you

The combustion fan is not reaching or holding the commanded speed.

Applies to: Navien NPE-A2 (built-in recirculation) and NPE-S2 condensing tankless water heaters: NPE-150S2, NPE-180A2/S2, NPE-210A2/S2, NPE-240A2/S2

Likely causes

  • Dirty air intake filter
  • Fan motor or wiring fault
  • Vent restriction

Test and repair steps

  1. Clean the air intake filter (manual's listed action).
  2. Run Service menu > 3. Test Mode > 1. Fan Motor: the fan ramps from 0 to max and back; check for noise or sticking.
  3. Check Status Information > 13. Current RPM while firing.
  4. Check the fan connector and wiring.
  5. Reset once with the Back button on the front panel and note whether the code returns.
  6. Code back after a reset? Stay at the unit and phone Navien Technical Support, 1-800-519-8794.

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Source: Navien NPE-A2/S2 User's Information Manual (20049624A), 5.2 Understanding Error Codes, p.17. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.