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Navien Knowledge Base

Your reference for Navien tankless water heaters — look up error codes, troubleshoot common problems, and learn how to keep your unit running. Serving Albany and the Capital Region. When you'd rather have a certified pro handle it, we're a call away.

Reference

Navien error code guide

Search common Navien fault codes to see what they mean and what to try. If a code keeps returning after a reset, it's time to call a certified technician.

Showing all 14 codes

Code	Meaning	Recommended Action
E003	Ignition failure	Check gas supply, igniter, and flame rod; verify gas pressure.
E004	False flame detected	Inspect flame rod wiring and ground; check for stray voltage.
E012	Flame loss during operation	Confirm steady gas pressure and clean the burner/flame rod.
E016	Overheating / abnormal high temp	Flush the heat exchanger to clear scale; check for blockages.
E030	Exhaust (flue) sensor fault	Inspect exhaust sensor and venting for obstruction or condensate.
E041	Hot water outlet sensor open	Test and replace the outlet thermistor; check harness connection.
E045	Inlet water sensor fault	Verify inlet sensor wiring; replace thermistor if out of range.
E067	Air pressure / fan sensor	Check the fan, air pressure tubing, and intake for blockage.
E110	Exhaust blockage / vent issue	Clear intake and exhaust vents; verify correct vent length & slope.
E210	Air pressure sensor abnormal	Inspect APS tubing for water/kinks; confirm fan operation.
E351	Cascade communication error	Check cascade cabling and address settings between units.
E438	Dip switch setting error	Verify dip switch configuration matches the install manual.
E515	PCB / abnormal main control	Power cycle the unit; if persistent, the PCB needs service.
E760	Wi-Fi / NaviLink comm error	Re-pair the NaviLink module and confirm router connectivity.

Common problems

Troubleshooting guide

The tankless issues we're called about most — what you'll notice, and what usually causes it.

No hot water at all

Symptom: Taps run cold and the unit may show an ignition code (E003).

Usually a gas-supply or ignition issue: a closed gas valve, tripped breaker, an empty propane tank, or a dirty flame rod. Confirm gas and power first; if the igniter clicks but never lights, the unit needs service.

Water is warm but never hot enough

Symptom: Output temperature sags, especially at multiple fixtures.

Often scale buildup on the heat exchanger or undersized gas/flow for demand. A descaling flush restores output in most cases; persistent low temps can indicate a failing flow sensor or mixing issue.

Hot water comes and goes ("cold water sandwich")

Symptom: A burst of hot, then cold, then hot again.

Normal to a degree with tankless units, but worsened by short cycling, low flow, or a failing flow sensor. A recirculation system or buffer tank smooths it out; sudden onset warrants a flow-sensor check.

Rumbling, popping, or whistling noises

Symptom: Kettle-like sounds during operation.

A classic sign of mineral scale inside the heat exchanger — common with the Capital Region’s hard water. An annual vinegar flush clears it and prevents premature failure.

Error code keeps returning after a reset

Symptom: You reset the unit and the same code comes back.

A code that returns is telling you a component actually needs attention (sensor, fan, gas pressure, venting). Repeated resets can mask a safety issue — this is the point to call a certified technician.

Care & upkeep

Maintenance facts

A well-maintained Navien lasts far longer. Here's what matters most.

How often should a Navien tankless be descaled?

Once a year for most homes. On hard water (common across Albany and the Capital Region), every 6–12 months keeps the heat exchanger clear and protects efficiency.

How long does a Navien tankless water heater last?

Typically 15–20 years when maintained — roughly double a standard tank — but only if it’s flushed regularly and the inlet filter is kept clean.

Does skipping maintenance void my warranty?

It can. Navien warranties expect documented annual service. We provide a service report after every visit so your coverage stays valid.

Questions

Frequently asked

Are you actually Navien certified?

Yes — Trinity Plumbing is a Navien Certified Specialist at Level 3, the top service tier. Our Navien HVAC certification is in progress and coming soon.

Do you repair all Navien models?

We service the full tankless lineup, including the NPE, NPE-2, NCB combi-boilers, and NHB boiler series, plus NaviLink Wi-Fi modules.

Can I just reset the unit myself?

A single reset after a one-off fault is fine. If the same code returns, stop resetting — it usually points to a real fault, and repeated resets can hide a safety problem.

How fast can you come out?

We offer same-day appointments in most of the Capital Region and 24/7 emergency service when you have no hot water.

Do you charge for a diagnosis?

We quote flat-rate, up-front pricing before any work begins — no surprises, and you approve the cost before we start.

Should I repair or replace my tankless unit?

If your unit is under about 10 years old and the repair is a sensor, fan, or flush, repair almost always wins. We’ll give you an honest recommendation either way.

Rather not troubleshoot it yourself?

Our Navien Certified Level 3 techs diagnose it fast — usually same day.

Call a technician

Code you can't clear? We can.

Trinity Plumbing's certified technicians repair every Navien series across Albany and the Capital Region.

Request a quote (518) 348-3032