Navien Error Code E238: Abnormal recirculation pump operation ● The pump is turned ON. ● Water flow is N
How to Fix Navien Code E238
- Step 1: Check that all valves in the recirculation loop are fully open. Sometimes a partially closed valve can restrict flow.
- Step 2: Try power cycling the Navien unit by turning it off and then back on. This can sometimes clear a temporary error.
- Step 3: If the problem persists, contact a qualified HVAC technician to diagnose and repair the issue.
How to Reset Navien Code E238
- 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 E238 Mean?
The Navien E238 error code indicates an issue with the recirculation pump's operation. Specifically, the unit detects that the pump is running, but it's not sensing the expected water flow. This is a problem because Navien tankless units rely on proper water flow to heat water efficiently and safely. Without adequate flow, the unit can overheat, leading to potential damage or safety risks. The recirculation pump is designed to keep hot water readily available at your fixtures, and this error means that system is not working as intended.
Common Causes
- Air lock in the recirculation loop preventing proper flow.
- Recirculation pump failure (pump motor not working or impeller damaged).
- Clogged recirculation piping or strainer restricting water flow.
- Faulty flow sensor preventing accurate flow detection.
- Wiring or electrical connection issue with the recirculation pump or flow sensor.
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Unit displays E238, pump is running | Measure voltage to the recirculation pump motor | Nominal voltage (usually 120VAC) when pump is energized |
| Pump voltage is present, but no flow is detected | Inspect the pump impeller for damage or blockage | Impeller is intact and rotates freely |
| Pump seems functional | Check the flow sensor signal while the pump is running | Flow sensor provides a signal indicating adequate flow rate |
| Low or no flow signal from flow sensor | Check the resistance of the flow sensor | Resistance within specified range per Navien service manual |
Applicable Navien Models
Source Documentation
Referenced in 1 official Navien technical manual.
| Manual | Page | Reason | Action |
|---|---|---|---|
| Navien NPF Installation & Operation Manual | 126 | Abnormal recirculation pump operation ● The pump is turned ON. ● Water flow is NOT detected. | This error occurs when the sensor on the furnace for recirculation pump operation 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 |
|---|---|---|---|
| Recirculation Pump | 30012413A | — | Find Part |
| Flow Sensor | 30010793A | — | Find Part |
| PCB Main | — | — | — |
Related Codes on Same Models
Other codes that affect the same Navien model families as E238.
| 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 |