- Boilers
- Tankless gas water heater
E515
Navien E515 on a tankless water heater: abnormal PCB operation
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
The heater's control board reported abnormal operation. Navien's action is to make sure the power cord is properly grounded. Reset once with the Back button; if E515 returns, call an authorized technician or Navien support.
Safety first
Stop and check this first
- Do not remove the front cover to look inside: Navien warns that operating the heater with the front cover open can cause fire or carbon monoxide poisoning, and that the cover may only come off with the power disconnected.
Safe checks you can perform
- Plug and outlet
- One reset with the Back button
- Grounding test
Leave these tasks to a qualified professional
- Do not attempt this professional task: Verify grounding and supply
- Do not attempt this professional task: Diagnose the control board
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Verify grounding and supply
What they doThe professional tests outlet ground and checks the cord and supply to the heater.
They must show youthe test result.
In writingwhat was corrected.
Diagnose the control board
What they doIf supply is correct and E515 persists, the technician diagnoses the PCB following Navien's service procedures.
They must show youthe code persisting with correct grounding.
In writingboard part number and reason.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Plug and outlet
- Who:
- you.
- How:
- look at the plug and outlet without touching anything wet. Navien supplies a 3-pronged grounded plug, says it can go into any grounded outlet nearby and not to use a broken or modified cord.
- Result that matters:
- whether the plug goes straight into a 3-hole outlet with an undamaged cord.
- If there is an adapter, extension or damage:
- tell the technician or an electrician.
- If not:
- grounding still needs testing.
- Evidence to keep:
- photo of the plug and cord.
Evidence: Navien NPE-A2 and NPE-S2 installation and operation manual
One reset with the Back button
- Who:
- you.
- How:
- press the Back button on the front panel. Navien's manual says resetting may solve the problem when an error appears.
- Result that matters:
- whether E515 comes back.
- If the heater runs normally:
- note the date; if E515 returns later, mention that it was reset before.
- If E515 returns:
- do not keep resetting; Navien says to contact an authorized technician, a licensed professional or its technical support.
- Evidence to keep:
- photo of the code before and after the reset.
Evidence: Navien NPE-A2 and NPE-S2 user's information manual
Grounding test
- Who:
- an electrician or licensed technician.
- How:
- tests ground and polarity at the outlet.
- Result that matters:
- whether the outlet is grounded.
- If it is not:
- it is corrected and the heater reset.
- If it is:
- the board is checked.
- Evidence to keep:
- written test result.
Work at mains voltage.
Evidence: Navien NPE-A2 and NPE-S2 user's information manual
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- Navien
- Product type
- Tankless gas water heater
Known code variants
- calentador Navien E515
- Navien 515
- Navien E515
- Navien E515 PCB
- Navien E515 placa PCB
- Navien error E515
What it means
Navien defines E515 as abnormal operation of the PCB, the heater's main control board. The only owner action in its manual is to ensure the electrical cord is properly grounded. A grounding or supply problem can make the board report this code, so the code alone does not prove the board must be replaced; a technician has to rule out the electrical supply first.
Warnings and stop conditions
- Highsource verified
Do not remove the front cover to look inside: Navien warns that operating the heater with the front cover open can cause fire or carbon monoxide poisoning, and that the cover may only come off with the power disconnected.
Evidence: Navien NPE-A2 and NPE-S2 installation and operation manual
Symptoms and causes
Probable causes · in order
- Grounding or electrical supply problemPossible
Navien's owner action for E515. Fits with adapters, extensions or outlets of unknown grounding.
Evidence: Navien NPE-A2 and NPE-S2 user's information manual · Navien NPE-A2 and NPE-S2 installation and operation manual
- Control board faultPossible
If grounding and supply test correctly, the board itself becomes the suspect. Only a technician can confirm it.
Evidence: Navien NPE-A2 and NPE-S2 user's information manual
Virtual technician
Does E515 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Navien NPE-A2 and NPE-S2 user's information manual
Navien · 2020 · manual
- 2
Navien NPE-A2 and NPE-S2 installation and operation manual
Navien · 2026 · manual
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