Navien E011 Error Code — What It Means
The E011 error code on a Navien tankless water heater indicates a high water pressure fault or a problem with the water pressure sensor. The unit has detected a pressure condition outside normal operating range, either because incoming water pressure is actually too high or because the sensor is misreading the pressure. The water pressure sensor is the first component Navien identifies in connection with this code. Keep in mind that code definitions can vary slightly by model family, so confirm the exact meaning in your unit’s service manual or with Navien support before ordering parts.
Common Causes
- Faulty water pressure sensor The sensor may be misreading pressure due to internal failure, loose wiring, or corrosion at the connector.
- Actual excessive incoming water pressure Your home’s water supply pressure may be higher than the heater’s operating range, triggering the fault.
- Debris or scale blocking the sensor port Mineral buildup or sediment can plug the small sensing path and cause false high-pressure readings.
- Trapped air or hydraulic surge in the plumbing Air pockets or pressure spikes from quickly closing valves can momentarily confuse the sensor.
- System leaks allowing continuous fresh water entry A slow leak that keeps the unit cycling fresh water can introduce minerals that foul the sensor over time.
Step-by-Step Fix
- {‘lead’: ‘Verify the model and confirm E011 in your manual’, ‘text’: “Check your unit’s model-specific service documentation to confirm that E011 means high water pressure or pressure sensor fault, since code lists differ across Navien families.”}
- {‘lead’: ‘Measure actual incoming water pressure with a gauge’, ‘text’: ‘Attach a pressure gauge to a hose bib or service valve upstream of the heater to see whether supply pressure is genuinely high, rather than trusting the code alone.’}
- {‘lead’: ‘Turn off power and water, then inspect the pressure sensor’, ‘text’: ‘Locate the water pressure sensor (consult your service manual for position), disconnect the wiring harness, and check the connector and sensor body for corrosion, moisture, or debris.’}
- {‘lead’: ‘Remove and clean the sensor port’, ‘text’: ‘Unscrew the sensor, flush the sensing port with clean water or vinegar solution to clear any scale or sediment, then dry and reinstall the sensor with a new seal if needed.’}
- {‘lead’: ‘Exercise the pressure relief valve near the outlet’, ‘text’: ‘Open and close the pressure relief valve a few times to flush debris that may be affecting flow and pressure sensing, as recommended by Navien for sensor and flow issues.’}
- {‘lead’: ‘Test the unit and observe the display’, ‘text’: ‘Restore power and water, run a hot tap to call for heat, and watch for the E011 code to clear or reappear.’}
- {‘lead’: ‘Replace the water pressure sensor if the fault persists’, ‘text’: ‘If the error returns and measured supply pressure is normal, order a genuine Navien water pressure sensor for your model and swap the old one, making sure the new sensor seats fully and the o-ring is in place.’}
Parts Often Needed
| Part | Notes |
|---|---|
| Navien water pressure sensor | Amazon | Order by your heater’s model number to get the correct sensor thread and connector. |
| Sensor o-ring or seal | Amazon | Often included with a new sensor, but check and replace if installing a used or aftermarket part. |
When to Call a Pro
If you are not comfortable working with gas or electrical connections, or if you cannot access the sensor location safely, call a licensed plumber or Navien service technician. Also call a pro if measured water pressure is genuinely excessive and you need a pressure-reducing valve installed upstream, or if the code persists after sensor replacement and cleaning. Any electrical testing of sensor resistance or voltage should be done by a technician with your model’s service manual, since the search results do not provide Navien’s factory test values for E011.