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Troubleshooting code

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Navien NFB-C Series E016 troubleshooting

Heat exchanger overheat. Use this page to document the issue and prepare for service. GreenFlow should handle diagnosis for electrical, refrigerant, lockout, or recurring conditions.

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What the code means

E016: Heat exchanger overheat

The Navien manual for this product family lists E016 as: Heat exchanger overheat.

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Equipment control
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Safe checks before calling

  • Record the exact Navien code, whether the unit is locked out, and when the code appeared.
  • Confirm thermostat, controller, or front-panel status without changing service settings.
  • Check only visible intake, exhaust, filter, clearance, condensate, and water-supply conditions that can be inspected without opening panels.
  • Take photos of the code, equipment nameplate, venting, surrounding equipment area, thermostat or controller, and any visible leak, ice, or obstruction.

When to stop and call GreenFlow

Call GreenFlow if the code repeats, the unit is locked out, hot water, heating, or cooling is not restored, or the concern involves gas, flame, combustion, venting, electrical components, refrigerant, pressure, water leaks, PCB/control boards, sensors, pumps, or warranty coverage.

Share the visible code, model and serial number if available, photos, current symptoms, and whether the issue affects heating, cooling, or both.

E016 questions

What does E016 mean on a Navien NFB-C Series?

The Navien manual for this product family lists E016 as: Heat exchanger overheat.

What should I safely check before scheduling service?

Record the displayed code, confirm thermostat or controller status, check only visible intake, exhaust, filter, clearance, and water-supply conditions, and take photos of the code and nameplate. Do not open gas, electrical, refrigerant, combustion, or internal equipment panels.

When should GreenFlow handle this code?

Call GreenFlow if the code repeats, the unit is locked out, hot water, heating, or cooling is not restored, or the concern involves gas, flame, combustion, venting, electrical components, refrigerant, pressure, water leaks, PCB/control boards, sensors, pumps, or warranty coverage.

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Andrey always does a great job.

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I needed 2 new AC units and decided to go with high efficiency heat pumps. I chose Greenflow because of the equipment they offered, and the price (2nd lowest quote and much cheaper than the average of all quote we received). Their technicians were very detail oriented and...

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They showed up within an hour of me making the call on a Sunday. They fixed our system and taught us how to replace the fuse in the future. We would definitely call again.

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