Rinnai · Tankless Water Heater Serious
11 — No Ignition
The unit attempted to ignite but failed to detect a flame within the trial-for-ignition period. Most common Rinnai fault code.
- Keep using it?
- Limited use only
- DIY difficulty
- Moderate
- Verified against
- rinnai.us ↗
How to fix it
- Verify gas valve to unit is fully open and other gas appliances work.
- For propane, confirm tank has fuel and regulator isn't iced.
- Purge air: run a stove burner or other gas appliance for a few minutes.
- Power-cycle the unit and try a hot tap.
- Remove front cover and inspect the igniter and flame rod — clean flame rod with fine sandpaper.
- Have a tech measure inlet gas pressure at the unit, static and dynamic.
- Replace igniter, flame rod, or gas solenoid based on findings.
Why it happens
Typical signs: No hot water · Click or fan but no burner · Code 11 immediately on hot water demand
- Gas supply off or low Closed valve, empty propane tank, or undersized gas line.
- Air in gas line Common after new installation or tank refill.
- Wrong gas pressure Inlet pressure outside spec (NG ~7" WC, LP ~11" WC static).
- Failed igniter or flame rod Cracked ceramic igniter or carbon-fouled flame sensor.
- Bad gas solenoid valve Valve not opening on command.
- PCB fault Board not commanding ignition sequence.
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.
More Rinnai 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: rinnai.us.