E302
Navien Low Water Pressure / Flow Fault

Navien water heater shows E302; unit may lock out and require reset.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Insufficient incoming water pressure, Clogged inlet filter, Partially closed isolation valve, Faulty flow sensor reading low flow

How to Fix / Troubleshooting

Safety: Turn OFF power and close water valves before removing filters.

Steps:

  • 1. Check household water pressure: Ensure other fixtures have normal pressure. If whole-house pressure is low, contact your water supplier or plumber.
  • 2. Verify valves are open: Confirm the cold water inlet valve at the Navien and any upstream valves are fully open.
  • 3. Clean inlet filter: Remove and clean the cold water inlet filter screen to remove sediment.
  • 4. Inspect flow sensor: If E302 persists, clean or replace the flow sensor as described for E032.

Persistent low-pressure faults may require a booster pump or plumbing corrections; consult a professional.

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Repair Difficulty

Medium 3/5

Required Part

Cold Water Inlet Filter Screen
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