Navien E515 Error Code — What It Means
Error code E515 (or 515-09) on your Navien tankless water heater means the control board has detected a fault in its own operation or communication path. The unit may lock out to protect itself. Some models display subcodes that point to specific circuits like the ignitor, fan motor, monitoring device, or dual venturi assembly. Because this is an internal control fault, the heater typically stops heating until the problem is cleared or the defective component is replaced.
Common Causes
- Failed main PCB The control board itself has failed due to component wear, manufacturing defect, or board revision issue and must be replaced.
- Loose or corroded PCB connections Wiring harness connectors to the control board are loose, corroded, or not fully seated, interrupting communication.
- Power surge or electrical disturbance A voltage spike or surge damaged sensitive components on the control board, leaving burn marks or a failed circuit.
- Faulty peripheral component A failed ignitor, fan motor, or dual venturi monitoring device sends abnormal feedback that the PCB interprets as a board fault.
- Firmware or board version mismatch Some field reports link the error to specific PCB revisions, suggesting certain board versions are more prone to the fault.
Step-by-Step Fix
- Verify the full code and subcode displayed on the unit, noting your exact model number, because Navien code families vary by model series.
- Power-cycle the heater by switching off the main power or unplugging the unit for 5 to 30 minutes to clear transient faults, then restart and observe.
- Turn off power and inspect the main PCB wiring harness for loose, corroded, or heat-damaged connectors, reseating every plug firmly and checking for pin fit.
- Examine the control board visually for burn marks, discoloration, swollen components, or odor that indicate surge damage or board failure.
- Check the subsystem named by your subcode if applicable: inspect ignitor circuit, fan motor wiring, or dual venturi monitoring device connections and operation.
- Replace the main PCB if visual damage is present, connectors are intact, and the code returns after a power cycle, using the correct board revision for your model.
- Re-test the unit through a full ignition and heating cycle after repair to confirm the E515 clears and the heater operates normally without recurrence.
Parts Often Needed
| Part | Notes |
|---|---|
| Navien main PCB / control board | Amazon | Match your model number exactly. Field-reported part number 30027274B (PCB GWC303-6M V12-2) applies to specific models only. |
| Ignitor assembly | Amazon | Only if your subcode points to ignitor communication fault and visual inspection or resistance test shows failure. |
| Fan motor | Amazon | Required if subcode indicates fan circuit abnormality and motor does not spin freely or draws incorrect current. |
When to Call a Pro
Call a licensed plumber or Navien-certified technician if you are uncomfortable working with 120V or 240V electrical components, if the error returns after reseating connectors and power-cycling, or if you lack the tools to safely remove and replace the control board. PCB replacement requires matching the exact board revision to your model and may involve firmware considerations. If your unit is under warranty, contact Navien or your installer before attempting any repair to avoid voiding coverage.