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Navien E016 Error Code: Heat Exchanger Overheat

Overheating — the outlet or heat exchanger temperature exceeded safe limits.

Service soon

Call (408) 470-0191Get this diagnosed

Open 24/7 · CSLB #1008381 · Joseph J. Castro, Owner

Navien tankless water heater control panel showing error code E016

Quick answer

Navien E016 means: Overheating — the outlet or heat exchanger temperature exceeded safe limits. It's usually caused by scale buildup in the heat exchanger, restricted flow, or a failed temperature sensor. The fix: Descale the heat exchanger, verify flow rate and filters, and replace out-of-spec sensors. Efficient Water Heaters, Inc. diagnoses Navien E016 faults across San Jose 24 hours a day, 7 days a week — (408) 470-0191, CSLB #1008381.

What you'll notice with E016

  • Hot water cuts out during long showers or tub fills
  • Reduced flow at the tap compared with a year ago
  • Rumbling or kettling sound while the unit runs

What causes it

Scale buildup in the heat exchanger, restricted flow, or a failed temperature sensor.

Safe steps you can take right now

  1. 1Check that the cold-water inlet valve is fully open.
  2. 2Remove and rinse the inlet filter screen if you're comfortable doing so.
  3. 3Don't keep resetting — the unit is preventing damage to the heat exchanger.

How we fix E016

In Santa Clara Valley water, E016 is a scale code far more often than a sensor code. We descale the exchanger, verify flow rate against the unit's rating, clean the inlet screen, and only then test the temperature sensors. Annual descaling prevents most repeat visits.

Descale the heat exchanger, verify flow rate and filters, and replace out-of-spec sensors.

Get your Navien E016 fixed

Call (408) 470-0191 any hour, or send the form and we'll reach out.

Send a photo of your data plate for a faster estimate.

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Navien E016 questions

Other Navien codes

Related: Navien repair in San Jose · descaling service · 24/7 emergency repair · all error codes

Navien E016 — related services, cities, and codes

E016 rarely shows up alone. These are the services that resolve it, the cities we cover, and the codes that often appear alongside it.