What you'll notice with E407
- Water runs much hotter or colder than the setpoint
- Unit short-cycles during a draw
- Display temperature doesn't match what you feel at the tap
Navien E407 Error Code: Water Temperature Sensor Abnormality
Water sensor abnormality — the unit reads an out-of-range water temperature signal.
Service soon
Open 24/7 · CSLB #1008381 · Joseph J. Castro, Owner
Quick answer
Navien E407 means: Water sensor abnormality — the unit reads an out-of-range water temperature signal. It's usually caused by faulty inlet/outlet thermistor, connector corrosion, or scale-coated probe. The fix: Test and replace the affected thermistor, clean connections, and descale if scale is present. Efficient Water Heaters, Inc. diagnoses Navien E407 faults across San Jose 24 hours a day, 7 days a week — (408) 470-0191, CSLB #1008381.
What causes it
Faulty inlet/outlet thermistor, connector corrosion, or scale-coated probe.
Safe steps you can take right now
- 1Verify nobody changed the setpoint at the control panel or in NaviLink.
- 2Avoid using the unit at high temperature until it's checked — scald risk.
- 3Book service.
How we fix E407
We test the inlet and outlet thermistors, clean corroded connectors, and check for scale coating the probe. Scaled sensors read low and drive the burner too hard, so we usually pair the repair with a descaling.
Test and replace the affected thermistor, clean connections, and descale if scale is present.
Get your Navien E407 fixed
Call (408) 470-0191 any hour, or send the form and we'll reach out.
Navien E407 — related services, cities, and codes
E407 rarely shows up alone. These are the services that resolve it, the cities we cover, and the codes that often appear alongside it.