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Navien tankless water heater code E515: meaning and exact next steps

E515 means Abnormal communication between the PCB and another component. Sub-codes 1 to 7 are PCB and ignitor communication, sub-code 8 is PCB and ignitor, sub-code 9 is PCB and fan, sub-code 10 is the PCB's monitoring device, and sub-codes 11 and 12 are PCB and Dual Venturi. This answer applies only to Navien NPE-series condensing tankless water heaters covered by Navien's NPE Service Manual, Version 2.21. Codes appear as E followed by three digits, some with a sub-code shown in the diagnostic mode. Confirm your model's own manual for newer units.

On the covered Navien tankless water heater, E515 means abnormal communication between the PCB and another component. Sub-codes 1 to 7 are PCB and ignitor communication, sub-code 8 is PCB and ignitor, sub-code 9 is PCB and fan, sub-code 10 is the PCB's monitoring device, and sub-codes 11 and 12 are PCB and Dual Venturi. First, reset the heater once from its front panel.

Part of Navien tankless water heater error codes guide

Differential

Likely causes of “Navien tankless water heater code E515”, and how to tell them apart

  1. 1

    A loose PCB connection

    What separates it E515 with a sub-code from 1 to 12 and a heater that stops

    How to confirm A technician reseats the connectors named by the sub-code

  2. 2

    A fan or ignitor communication fault

    What separates it Sub-codes 8 and 9 name the ignitor and fan

    How to confirm Listen for the fan starting and look for ignition

  3. 3

    A Dual Venturi communication fault

    What separates it Sub-codes 10 to 12 name the monitoring device and the venturi

    How to confirm A technician checks the venturi harness

Before you touch a setting

Record this first — changing settings destroys the evidence

  • The sub-code shown after E515
  • Whether hot water stops at once
  • The heater model and serial
  • Whether the heater was serviced lately

Try in this order

0 of 5 completed

  1. What to do first

    Reversible

    Reset the heater once from its front panel.

  2. Correct only the documented fault domain

    Reversible

    Navien's actions: check the PCB (sub-codes 1 to 7); check the PCB connection and the ignitor (8); the PCB connection and the fan (9); the PCB connection and the Dual Venturi (10 to 12). Board and connection work is for a technician.

  3. Note the sub-code

    Reversible

    The number after E515 says which component the board lost contact with.

  4. Reset the heater once

    Reversible

    Switch the heater off at its front panel and on again, then run hot water.

  5. Book service with the sub-code

    Reversible

    Navien's actions check the PCB, ignitor, fan or Dual Venturi connection depending on the sub-code.

Model-specific

What is true of this model and not of its siblings

Shown as
E515 with a sub-code.
Applies to
Navien NPE tankless water heaters.

Stop boundary

When this stops being a self-service repair

  • !Board and connection work is for a technician
  • !Call Navien support with the sub-code

Evidence ledger

Sources behind this answer

01
Navien NPE Service Manual, Version 2.21 — 5.1 Error Code List

Exact questions

Common questions

What does E515 mean on a Navien tankless water heater?+

Abnormal communication between the PCB and another component. Sub-codes 1 to 7 are PCB and ignitor communication, sub-code 8 is PCB and ignitor, sub-code 9 is PCB and fan, sub-code 10 is the PCB's monitoring device, and sub-codes 11 and 12 are PCB and Dual Venturi.

What does E515 mean?+

Abnormal communication between the PCB and another component.

Do the sub-codes matter?+

Yes. Sub-codes 1 to 7 are PCB and ignitor, 8 ignitor, 9 fan, 10 monitoring device, 11 and 12 Dual Venturi.

Is it a gas fault?+

It is a communication fault between boards and parts, not a gas supply message.

Wrong device or version?

Match the path before repeating the steps.

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