Rinnai Code 11: No Ignition — 7 Fixes That Work

Rinnai error code 11 means an ignition failure or lack of gas supply — the unit tried to light the burner and couldn’t. The most common causes are a closed or low gas valve, air trapped in a new gas line, and a dirty flame rod or igniter.

What This Means

The control board tried to open the gas valve and spark the igniter, but never confirmed a flame within the safety window. It locks out rather than keep trying with an open gas valve and no flame.

Illustration of a clean flame sensor rod next to a carbon-fouled one — fouling like this is a common cause of no-ignition faults.

Likely Causes, Ranked

Gas supply issue
Main gas valve partly closed, or gas pressure too low to sustain ignition.
Air in the gas line
Common right after a new install, after gas-line work, or if the unit sat unused a long time.
Dirty flame rod or igniter
Carbon or sulfur buildup stops the sensor from detecting a flame that’s actually there.
Blocked burner assembly
Dust, insects, or spiderwebs clogging the burner or the air intake.
Frozen or faulty regulator (propane, cold climates)
Owners in cold regions report code 11 spiking in freezing weather.

Step-by-Step Diagnosis

DIY SAFE
Confirm the gas valve is fully open

Handle should be parallel to the pipe. A quarter-turn closed is enough to cause this.
DIY SAFE
Check for other gas appliances competing for supply

Furnace or stove running at the same time can starve a marginal gas line.
DIY WITH CAUTION
Purge air from the line (new installs only)

Follow the unit’s purge procedure in the install manual before repeated ignition attempts — repeated dry-fire attempts can foul the igniter.
DIY WITH CAUTION
Power off, then inspect the flame rod and igniter

Remove the front cover, locate the flame rod (usually front-lower on the burner assembly), and clean carbon buildup with fine sandpaper or emery cloth. Don’t use a wire brush — it can scratch the ceramic insulator.
DIY WITH CAUTION
Check for burner blockage

Look for insect nests or dust in the burner tray and combustion air intake.
PRO ONLY
Verify inlet gas pressure with a manometer

Natural gas: 3.5–10.5″ W.C. Propane: 8–13.5″ W.C. Outside these ranges points to a supply-side problem, not the water heater.
PRO ONLY
If pressure is out of range or the line was recently worked on

Call your gas utility or a licensed plumber — don’t adjust the regulator yourself.

Parts

Part	Note
Flame rod / electrode kit	Model-specific — cross-check your model plate against Rinnai’s parts lookup before ordering.

Models Covered

RL series, RU series, RUR/RUC series

FAQ

How do I fix code 11 on my Rinnai?

Check the gas valve is open, purge air if it’s a new install, then inspect and clean the flame rod. Most code 11s are gas supply or a dirty flame rod.

Should I call a plumber for Rinnai code 11?

If the gas valve is open and pressure looks right but the code keeps returning, yes — especially before touching the gas line or regulator.

How to clear Rinnai error code 11?

Power-cycle the unit after fixing the underlying cause. Cycling power without fixing anything usually brings the code straight back.

What are the common Rinnai error codes near code 11?

Code 12 (flame failure after ignition) and code 79 (leak sensor) are the two people most often confuse with 11.

Written by HotWater Decoded — water heater repair specialists. Technically reviewed by a licensed technician on our team.

Sources

Google’s AI Overview summary and JustAnswer/forum discussions
Gas pressure spec cross-checked against tanklesshelp.com’s published range