Navien · Tankless Water Heater Serious

E515 — PCB / Control Board Abnormal

Self-diagnostic detected an internal PCB malfunction — corrupted memory, watchdog reset, or relay feedback error.

Keep using it?
Limited use only
DIY difficulty
Hard
Verified against
navieninc.com ↗

How to fix it

  1. Power off at the breaker for 5 minutes, then restore — confirm code returns.
  2. Inspect the control compartment for moisture or burn marks; address any leak first.
  3. If code persists with no obvious external cause, replace the PCB.
  4. Install a whole-house or point-of-use surge protector after replacement.

Why it happens

Typical signs: E515 on display · Unit unresponsive · Random shutdowns · Display glitches

  • PCB failure Internal control board fault.
  • Power surge Lightning or surge damaged board components.
  • Moisture intrusion Condensate or leak reached the control compartment.

Parts you may need

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

  • Navien PCB / control board Common replacement
    Amazon →

More Navien tankless water heater codes

E003 E003 — Ignition Failure E003C E003C — Cascade Ignition Failure E012 E012 — False Flame / Flame Loss E016 E016 — Overheat / High-Limit Trip E027 Tankless E027 — Sensor Abnormality E030 E030 — Abnormal Exhaust Temperature (Flue Overheat)

All Navien codes → All tankless water heater codes →

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: navieninc.com.