Navien Error Code E047: DHW Thermistor Open/Short
Warning: Your Navien tankless water heater has detected a problem with the DHW thermistor and has shut down to prevent damage.
How to Fix Navien Code E047
- Check if the error persists after turning the power off and back on again.
- Inspect the wiring harness connecting the DHW thermistor to the control board for any signs of damage or corrosion.
- If the error remains, contact a licensed HVAC technician to diagnose and repair the issue.
How to Reset Navien Code E047
- 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.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Navien Error Code E047 Mean?
The E047 error on your Navien tankless water heater indicates an open or short circuit in the DHW (Domestic Hot Water) thermistor. This component is responsible for measuring the water temperature and signaling the control board to adjust the heating process. When the thermistor fails, it can cause the system to shut down to prevent overheating or freezing. Don't worry, this isn't a gas leak or fire risk, but it does require professional attention.
Common Causes
- A broken or faulty DHW thermistor
- Wiring issues between the thermistor and the control board
- Corrosion or damage to the thermistor due to hard water or scale buildup
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Error E047 is displayed | Measure the resistance of the DHW thermistor using a multimeter | A resistance value between 10,000 to 100,000 ohms (depending on the model and temperature) |
| Resistance is outside the expected range | Inspect the wiring and connections to the DHW thermistor | No visible damage, corrosion, or signs of overheating |
Applicable Navien Models
Source Documentation
Referenced in 6 official Navien technical manuals.
| Manual | Page | Reason | Action |
|---|---|---|---|
| NFB-H Installation & Operation Manual | 116 | Exhaust Thermistor | Check thermistor connector. |
| Navien NCB-H Installation & Operation Manual | 129 | Exhaust Thermistor | Contact technical support at 1-800-519-8794. |
| Navien NFB-H Installation & Operation Manual | 116 | Exhaust Thermistor | Check thermistor connector. |
| Navien NFC-H Installation & Operation Manual | 127 | Abnormal operation: exhaust thermostat | Manual RESET Auto RESET |
| Navien NHB-H Installation & Operation Manual | 119 | Exhaust Thermistor | Check thermistor connector. |
| Navien NPF Installation & Operation Manual | 126 | Abnormal exhaust temperature sensor operation | This error occurs when the exhaust temperature sensor does not operate properly. ● Turn off the furnace, turn it on again and check if the furnace operates properly. ● If the furnace is continuously inoperable, contact Technical Support at 1-800-519-8794. |
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| DHW Thermistor | 3200010001 | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Navien model families as E047.
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E110 | Exhaust Blocked | Warning |
| E205 | Water Flow Sensor Failure | Warning |
| E517 | Water Flow Switch Failure | Warning |
| E736 | CH Return Thermistor Failure | Warning |
| E740 | CH Buffer Tank Thermistor | Warning |