HVACopedia

Navien · Combi boiler

E004 False flame detected

High severity Navien NCB-HNavien NFC-H

What the control is telling you

The control sees a flame signal when there should be no flame. NFC-H manual lists the reset type as: Manual reset / Auto reset.

Applies to: Navien fire-tube combi boilers, NFC-H series (NFC-250/200H, NFC-250/175H) and NCB-H combi boilers (NCB-250/150H, NCB-240/130H, NCB-240/110H, NCB-190/080H, NCB-190/060H)

Likely causes

  • Poor electrical ground on the power cord/outlet
  • Moisture or deposits on the flame detector electrode
  • Gas valve not closing fully

Test and repair steps

  1. Make sure the power cord/outlet is properly grounded (the manual's listed remedy).
  2. Check Status Information > 17. Flame Value with the burner off: flame-off reads 175 or higher; flame-on reads 70 or lower.
  3. Remove, inspect and clean the flame detector electrode and check its gasket.
  4. Warning: if a flame is still present after the gas valve closes, shut the manual gas valve and do not run the boiler until the gas valve is checked.
  5. Code keeps returning? Phone Navien Technical Support, 1-800-519-8794.

Settings for these units

Save it for the next call

Star this code in the HVACopedia app and keep the whole library on your phone for jobs with no signal.

Open the app

Source: Navien NCB-H Installation & Operation Manual, 11.7 Understanding Error Codes, p.129-130; Navien NFC-H Installation Manual, 11.7 Understanding Error Codes, p.127-128. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.