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Navien boiler error code E515: abnormal PCB

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HHW · ERROR-CODES · NAVIEN-BOILER · E515
Based on
Navien User's Information Manuals and Installation & Operation manuals

Short answer On Navien boilers, E515 points to the circuit board (PCB). On the NCB-H and NCB-E the manual's steps are to make sure the electrical cord is properly grounded and reset once; if E515 returns, call an authorized technician or Navien Technical Support. See what to check

Boiler front panel display

E515

“Abnormal PCB”

Owner checks, then technician

Printed on 5 model series · 5 documents

NCB-H, NCB700, NFC-H, NFB-H, NHB-H · NCB-H user's manual (January 2025) p. 26; NCB700 installation manual (July 2026) p. 137; NFC-H user's manual (April 2024) p. 24; NFB-H user's manual (April 2024) p. 23; NHB-H installation manual (April 2026) p. 119

What it means

E515 points to the boiler’s PCB (printed circuit board). The NCB-H, NCB700, NFC-H, NFB-H and NHB-H tables call it “Abnormal PCB” (navien-ncb-h-um-2501, p. 26; navien-ncb700-io, p. 137; navien-nfc-h-um-c, p. 24; navien-nfb-h-um, p. 23; navien-nhb-h-um, p. 24). The NCB-E and NFC tables say “Abnormal operation: PCB”, and the NFB, NHB, NFB-C and NFB700-C tables “Abnormal operation: PCB component” (navien-ncb-e-um, p. 22; navien-nfc-io, p. 101; navien-nfb-um, p. 20; navien-nhb-um, p. 22; navien-nfb-c-um, p. 19; navien-nfb700-c-io, p. 119). The tables do not say what on the board is abnormal.

Check these first

The NCB-H user’s manual gives two actions for E515: “Ensure that the electrical cord is properly grounded.” and “Reset the boiler from the front panel.” (navien-ncb-h-um-2501, p. 26). The NCB-E manual gives the same two (navien-ncb-e-um, p. 22), and so do the NCB700 and NFC installation manuals (navien-ncb700-io, p. 137; navien-nfc-io, p. 101).

  1. Make sure the boiler’s electrical cord is properly grounded (navien-ncb-h-um-2501, p. 26). The manual does not say how to check this. Among its service options it lists a licensed professional for the affected system, for example an electrician (navien-ncb-h-um-2501, p. 64).
  2. Reset the boiler from the front panel, once. On the NCB-H press Back (navien-ncb-h-um-2501, p. 13); on the NCB-E press Reset (navien-ncb-e-um, p. 11).
  3. If E515 comes back, the manual’s next step is an authorized technician, a licensed professional or Navien Technical Support at 1-800-519-8794 (navien-ncb-h-um-2501, p. 24). Have the model number, serial number, date purchased, installation location and type, and the error code ready (navien-ncb-h-um-2501, p. 64).

On the NFC-H, NFB-H and NHB-H the E515 row reads “Check PCB connections.” and does not say who checks (navien-nfc-h-um-c, p. 24; navien-nfb-h-um, p. 23; navien-nhb-h-um, p. 24). These manuals give the owner no procedure for the board. They say not to remove the front cover unless the power to the boiler is turned off or disconnected, and not to repair or replace any part unless the manual specifically recommends it (navien-nfb-h-um, p. 5). The reset on these three is the Back button (navien-nfc-h-um-c, p. 13; navien-nfb-h-um, p. 13; navien-nhb-h-um, p. 14).

When to call a licensed technician

  • E515 returns after the cord check and one reset (navien-ncb-h-um-2501, p. 24).
  • The PCB connection check from the NFC-H, NFB-H and NHB-H tables (navien-nfb-h-um, p. 23).
  • Anything inside the boiler. Navien tells owners not to repair or replace any part unless the user’s manual specifically recommends it (navien-ncb-h-um-2501, p. 5).

Notes for different models
Series and document Wording Action in the table Source
NCB-H user’s manual, NCB700 installation manual “Abnormal PCB” “Ensure that the electrical cord is properly grounded.” and “Reset the boiler from the front panel.” navien-ncb-h-um-2501, p. 26; navien-ncb700-io, p. 137
NCB-E user’s manual, NFC installation manual “Abnormal operation: PCB” The same two actions navien-ncb-e-um, p. 22; navien-nfc-io, p. 101
NFC-H, NFB-H, NHB-H user’s manuals “Abnormal PCB” “Check PCB connections.” navien-nfc-h-um-c, p. 24; navien-nfb-h-um, p. 23; navien-nhb-h-um, p. 24
NFC-H installation manual (March 2021) “Abnormal operation: PCB component” “Manual RESET Alarm” navien-nfc-h-io, p. 127
NFB, NHB, NFB-C user’s manuals, NFB700-C installation manual “Abnormal operation: PCB component” “Alarm/Manual reset/Power On reset” navien-nfb-um, p. 20; navien-nhb-um, p. 22; navien-nfb-c-um, p. 19; navien-nfb700-c-io, p. 119

The manuals do not explain the “Alarm”, “Manual reset” and “Power On reset” labels. The reset buttons on these boilers differ: Back on the NFB (navien-nfb-um, p. 10), Reset on the NHB (navien-nhb-um, p. 11), press and hold Reset on the NFB-C (navien-nfb-c-um, p. 10).

Navien’s tankless water heaters also have an E515, with their own table and remedies; see the Navien tankless table.

Related Navien boilers codes

  • E517 “Abnormal DIP Switch”
  • E594 “Abnormal EEPROM”
  • E615 “Abnormal Memory”

See also

Other gas boilers: Weil-McLain

All Navien boilers codes

Navien is a trademark of its owner. How House Works is not affiliated with or endorsed by Navien.

Sources

13 documents
  1. Navien, Inc.. User's Information Manual NCB-H Condensing Combi-Boilers. Version: 1.0 (January, 2025), part no. 20050970B. Accessed Oct 21, 2026.
  2. Navien, Inc.. Installation & Operation Manual NCB700 Condensing Combi-Boilers. Version: 1.0 (July, 2026). Accessed Oct 21, 2026.
  3. Navien, Inc.. User's Information Manual NFC-H Condensing Combi-Boilers. Version: 1.0 (April, 2024), part no. 20052125C. Accessed Oct 21, 2026.
  4. Navien, Inc.. User's Information Manual NFB-H Condensing Boilers. Version: 1.0 (April, 2024). Accessed Oct 21, 2026.
  5. Navien, Inc.. Installation and Operation Manual NHB-H Condensing Boilers. Version: 1.0 (April, 2026). Accessed Oct 21, 2026.
  6. Navien, Inc.. Installation Manual NFC-H Condensing Combi-Boilers. Version: 1.0 (March, 2021). Accessed Oct 21, 2026.
  7. Navien, Inc.. Installation & Operation Manual NFC Condensing Combi-Boilers. Version: 1.0 (Jan 25, 2019). Accessed Oct 21, 2026.
  8. Navien, Inc.. User's Information Manual NFB Condensing Boilers. Version: 1.0 (April, 2024). Accessed Oct 21, 2026.
  9. Navien, Inc.. Installation & Operation Manual NFB700 Commercial Condensing Boilers. Version: 1.0 (July, 2026). Accessed Oct 21, 2026.
  10. Navien, Inc.. User's Information Manual NFB Condensing Boilers. Version: 1.1 (July 4, 2018). Accessed Oct 21, 2026.
  11. Navien, Inc.. User's Information Manual NHB Condensing Boilers. Version: 2.0 (May 30, 2019), part no. 20032170C. Accessed Oct 21, 2026.
  12. Navien, Inc.. User's Information Manual NCB-E Condensing Combi-Boilers. Version : 6.0 (May 27, 2019), part no. 20035566B. Accessed Oct 21, 2026.
  13. Navien, Inc.. User's Information Manual NHB-H Condensing Boilers. Version: 1.0 (April, 2024). Accessed Oct 21, 2026.