Navien Error Code E407: Dom.Hot Water Outlet Sensor
How to Fix Navien Code E407
- Step 1: Turn the unit off and then back on again. This may clear a temporary error.
- Step 2: Check the wiring connections on the outside of the unit for obvious signs of damage or corrosion. Do not open the unit. If you see anything suspicious, call a technician.
- Step 3: If the error persists after restarting the unit, contact a qualified HVAC technician to diagnose and repair the problem.
How to Reset Navien Code E407
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
What does E407 mean?
The E407 error code on your Navien tankless water heater indicates a problem with the domestic hot water (DHW) outlet temperature sensor. This sensor is responsible for monitoring the temperature of the hot water as it leaves the unit and goes to your faucets. The Navien's control board uses this temperature reading to modulate the burner and maintain a consistent hot water temperature. If the sensor is faulty, disconnected, or reading an implausible value, the unit will shut down and display the E407 error to prevent overheating or other issues. Basically, the Navien doesn't know how hot the water is, so it's playing it safe by shutting down.
This error can stem from a few different issues, ranging from a simple wiring problem to a failing sensor. Because the Navien relies on accurate temperature readings to operate safely and efficiently, it's important to address this error promptly. While some basic troubleshooting can be done, this error usually requires a qualified technician to diagnose and repair.
Affected Models
- NCB-H
- NFB-H
- NFC-H
- NHB-H
- NHW-A
- NPE-A2
- NCB
- NCB
- NCB
- NPE
- NPE
- NPE
- NHB
- NHB
- NCB
- NCB
- NPE
- NPE
- NCB
- NCB
- NPE
- NCB
- NPE
- NHB
- NCB
- NPE
- NPE
- NCB
- NCB
- NPE
- NPE
- NPE
- NPE
- NHB
- NHB
- NCB
- NCB
- NPE
- NPE
- NBP
- NPE
- NPE
- NPE
- NFC
- NFC
- NCB
- NPE
- NPE
- NPE
- NCB
- NPE
- NCB
- NPE
- NPE
- NCB
- NPE
- NHB
- NPE-S
- NPN
- NPN
- NCB
- NPE
- NCB
- NPE
- NHB
- NPB
- NFC
- NFC
- NHB
- NPF
- NPF
- NPE
- NHB
Source Documentation
| Manual | Page | Reason | Action |
|---|---|---|---|
| Navien NCB-H Installation & Operation Manual | 129 | Dom.Hot Water Outlet Sensor | Contact technical support at 1-800-519-8794. |
| Navien NFC-H Installation & Operation Manual | 127 | Hot water outlet: thermistor open or short circuit | Auto RESET |
Recall Notices
LP gas conversion kits can cause units to produce excessive carbon monoxide.
Replacement Parts
| Part | OEM Number | Est. Cost |
|---|---|---|
| DHW Outlet Temperature Sensor | 30012345A | — |
| Main Control Board | 30008721B | — |
| Wiring Harness | — | — |
Related Codes on Same Models
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E012 | Flame Loss | Warning |
| E016 | Overheating | Warning |
| E030 | Exhaust Overheat Sensor | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E047 | DHW Thermistor Open/Short | Warning |
| E060 | Fan Motor Abnormality | Warning |