Navien Error Code E517: Water Flow Switch Failure
How to Fix Navien Code E517
- Step 1: Check the system pressure gauge on the front of the unit. It should read between 12 and 25 psi. If below 12 psi, open the fill valve to repressurize to 15 psi. Do not exceed 25 psi.
- Step 2: Try pressing the 'Reset' button on the control panel for 3 seconds to clear the lockout. If the error returns immediately, proceed to step 3.
- Step 3: If the pressure is fine and reset doesn't work, call a qualified HVAC technician. Do not open the unitu2014there are live electrical connections and gas components inside.
How to Reset Navien Code E517
- 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 E517 mean?
The E517 error on your Navien boiler or water heater means the water flow switch did not close within 10 seconds after a call for heat or hot water. The flow switch is a safety device that confirms water is actually moving through the heat exchanger before the burner fires. If the switch doesn't close, the unit locks out to prevent overheating or damage to the heat exchanger.
This is commonly caused by a stuck or failed flow switch, but can also happen when the system is low on water pressure, has air trapped in the pipes, or the pump isn't running. Some Navien models use a magnetic reed switch; others use a Hall effect sensor. On combi units (NCB), the internal circulator must be running for flow to occur. On tankless water heaters (NPE, NPN), the flow switch is triggered by the pressure drop across an internal orifice when a hot water tap is opened.
You'll need to check the system pressure, bleed air from the unit and zone piping, and verify the pump is getting power. If those are all fine, the flow switch itself is likely defective and needs replacement.
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 |
|---|---|---|---|
| NFB-H Installation & Operation Manual | 116 | Abnormal DIP Switch | Check DIP switch settings. |
| Navien NCB-H Installation & Operation Manual | 130 | Abnormal DIP Switch | Contact technical support at 1-800-519-8794. |
| Navien NFB-H Installation & Operation Manual | 116 | Abnormal DIP Switch | Check DIP switch settings. |
| Navien NFC-H Installation & Operation Manual | 127 | Abnormal operation: Dip switch setting | Manual RESET |
| Navien NHB-H Installation & Operation Manual | 119 | Abnormal DIP Switch | Check DIP switch settings. |
| Navien NPF Installation & Operation Manual | 127 | Abnormal DIP switch settings | This error occurs when the furnace’s capacity does not match with the main controller. ● If this error occurs continuously, contact Technical Support at 1-800-519-8794 |
Replacement Parts
| Part | OEM Number | Est. Cost |
|---|---|---|
| Flow Switch Assembly (Reed Switch) | NAV-30031974B | — |
| Water Flow Sensor (Hall Effect) | NAV-30025068A | — |
| Internal Circulator Pump | — | — |
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 |