Navien tankless and combi units use direct spark ignition — no standing pilot. The igniter creates a high-voltage spark across an electrode gap to light the burner. When it fails, the unit throws Code 003 (no ignition).
Diagnose first (don't just replace)
Many Code 003 faults trace to gas supply or flame rod issues, not igniter. Work through the Code 003 diagnostic sequence before ordering.
Confirm igniter failure
- Turn off gas (so no actual ignition)
- Trigger an ignition attempt by opening a hot tap
- In a dark room, look through the sight glass
- You should see a bright blue spark across the electrode gap
- No spark = igniter or igniter cable
Replacement (DIY)
- Power off and shut off gas
- Remove the front cover
- Locate igniter — ceramic-encapsulated probe with thick high-voltage cable
- Disconnect cable from PCB output (note orientation)
- Unscrew igniter from mount
- Install new igniter; reconnect cable
- Close cover, restore gas, power on
- Test — should hear ignition click and see blue flame
Cost
- OEM Navien igniter: $50-100 model-dependent
- OEM-equivalent on Amazon: $20-60 (voids warranty if used inside warranty period)
How often does it fail?
Direct spark igniters last 8-12 years in residential use. Faster in propane systems or short-cycling units.
Warranty
Covered under 5-year NPE parts warranty. Call 1-800-519-8794.
Bottom line
Visual confirmation before ordering. Replacement is straightforward DIY. See Code 003 page for full diagnostic order.