Modern Rinnai tankless units use direct spark ignition — no standing pilot. An igniter creates a high-voltage spark across an electrode gap to light the burner. When the igniter fails, the unit throws Code 11 (no ignition).
Diagnose first (don't just replace)
Many Code 11 faults trace to gas supply or flame rod issues, not the igniter. Work through the Code 11 diagnostic sequence before ordering an igniter.
How to confirm igniter failure
- Turn off gas (so no actual ignition)
- Trigger an ignition attempt by opening a hot tap
- In a dark room (or with a flashlight ready), look through the unit's sight glass
- You should see a bright blue spark across the electrode gap
- No spark = igniter or igniter cable
Replacement (DIY)
- Power off the unit and shut off gas
- Remove the front cover
- Locate the igniter — typically a ceramic-encapsulated probe with a thick high-voltage cable
- Disconnect the cable from the PCB output (note orientation)
- Unscrew the igniter from its mount
- Install new igniter; reconnect cable
- Close cover, restore gas, power on
- Test — should hear ignition click and see blue flame
Cost
- OEM Rinnai igniter: $40-90 model-dependent
- OEM-equivalent on Amazon: $20-50 (voids warranty if used inside warranty period)
- Igniter rebuild kit (igniter + gasket + cable): $80-120
How often does it fail?
Direct spark igniters last 8-12 years in residential use. Faster in propane systems or units with frequent short-cycling (poorly sized gas line, oversized unit for the home).
Warranty
Covered under the 5-year parts warranty on Sensei. Call 1-800-621-9419 with the serial number for warranty replacement.
Difference from older models
Legacy R-series (R75LS, R85, R94LS — 2003-2014) used a thermocouple-based pilot instead of direct spark. R-series fault patterns differ — see thermocouple page if you have a legacy unit.
Bottom line
Visual confirmation (sparking or not) before ordering. The replacement itself is straightforward DIY. See the Code 11 page for the full diagnostic order.