Navien E515 Error Code

What does Navien E515 mean?

E515 indicates an internal PCB communication fault. The main control board continuously exchanges data with the ignitor board, fan motor driver, dual venturi actuator, and 3-way valve; when any of these communication links fails — through a wiring fault, failed component, or the PCB itself — the board logs E515 and shuts the unit down. Subcodes within E515 point to the specific failed communication path.

Symptoms

• Unit locks out with E515 on the display; no ignition or heating occurs.
• Error code may include a subcode number indicating the failed subsystem.
• Unit does not respond to reset or immediately re-faults on startup.
• Peripheral components such as the fan or venturi may not operate at all.

Common causes

• Loose or damaged connector between the PCB and the ignitor board (subcodes 1–8).
• Fan motor or fan wiring fault losing PCB communication (subcode 9).
• Dual venturi wiring or actuator failure breaking PCB feedback loop (subcodes 10–12).
• Ground wire loose or missing, causing electrical noise that corrupts communication.
• PCB itself has failed internally.

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Diagnostic steps

1. Note the E515 subcode

   Read the full error display — the subcode number after E515 identifies which communication path failed. Subcodes 1–8 point to ignitor board, subcode 9 to the fan, and subcodes 10–12 to the dual venturi.

2. Verify the unit is properly grounded

   Confirm the chassis ground wire is securely connected to both the unit frame and the electrical panel ground. Poor grounding is a frequent source of PCB communication interference.

3. Inspect wiring harnesses at identified component

   Based on the subcode, locate the relevant component's wiring harness connector on the PCB. Disconnect, inspect for corrosion and bent pins, and reseat firmly. Also check the connector at the component end.

4. Inspect and test the identified peripheral component

   For the ignitor board, check for burn marks and confirm it powers on. For the fan, verify it spins freely and its connector is fully seated. For the dual venturi, run the test mode and observe actuator movement.

5. Replace failed component and retest

   Replace the component identified by the subcode with the OEM part. Restore power and observe whether E515 clears. If the code persists after component replacement and all wiring checks pass, the PCB itself has failed.

When to call a professional

PCB replacement on Navien units requires configuration transfer, DIP switch verification, and post-installation functional testing of all peripherals. This repair must be performed by a licensed technician with access to Navien's service documentation. Contact Navien Technical Support at 1-800-519-8794 to confirm the subcode diagnosis before ordering parts.