Navien Error Code E218: Bypass Servo Motor Failure
Warning: Your Navien boiler has detected a failure in the bypass servo motor, which may impact system performance. Schedule a professional repair soon.
How to Fix Navien Code E218
- Step 1: Turn off the boiler at the main power switch to ensure safety.
- Step 2: Check if the bypass valve is stuck or obstructed. If it's easy to turn, try gently moving it back and forth. If it's stuck, do not force it and call a professional.
- Step 3: If the issue persists, call a licensed HVAC technician to diagnose and repair the problem.
How to Reset Navien Code E218
- 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 E218 Mean?
The E218 error on your Navien boiler indicates a failure in the bypass servo motor. This motor is responsible for controlling the flow of water through the boiler's heat exchanger. When it fails, the boiler may not be able to maintain the correct water temperature, leading to inefficient heating. The error code will display on your boiler's digital display, and the unit will enter lockout mode to prevent further operation until the issue is resolved.
Common Causes
- Worn or faulty servo motor
- Obstruction in the water flow
- Incorrect motor wiring or connection issues
- Faulty control board or sensor
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Boiler is not heating water | Measure the temperature of the water entering and exiting the boiler. Use a thermometer or a multimeter with a temperature probe. | A temperature difference of at least 10-15 degrees Fahrenheit (5.5-8.3 degrees Celsius) between the inlet and outlet water. |
| Boiler is making unusual noises | Listen for any grinding, squealing, or clicking sounds coming from the servo motor area. | Normal operation should be quiet. Any unusual noises may indicate a faulty motor. |
Applicable Navien Models
Source Documentation
Referenced in 6 official Navien technical manuals.
| Manual | Page | Reason | Action |
|---|---|---|---|
| NFB-H Installation & Operation Manual | 116 | Heating Return Temp.Sensor | Check thermistor connector. |
| Navien NCB-H Installation & Operation Manual | 129 | Heating Return Temp.Sensor | Contact technical support at 1-800-519-8794. |
| Navien NFB-H Installation & Operation Manual | 116 | Heating Return Temp.Sensor | Check thermistor connector. |
| Navien NFC-H Installation & Operation Manual | 127 | Abnormal operation: heating return thermistor | Auto RESET |
| Navien NHB-H Installation & Operation Manual | 119 | Heating Return Temp.Sensor | Check thermistor connector. |
| Navien NPF Installation & Operation Manual | 126 | Abnormal return water-temp sensor operation for lower limit | — |
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Bypass Servo Motor | NAVIEN 30001400 | — | Find Part |
| Control Board | NAVIEN 30001200 | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Navien model families as E218.
| 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 |