Rinnai Code 11: No Ignition Fix for RU and V Series Tankless Heaters

Quick Answer

Rinnai Code 11 means ignition failed after 3 consecutive attempts with no flame detected. The most common cause is a dirty flame rod coated with oxide buildup, which prevents the rod from sensing ignition. Other causes include low or interrupted gas supply, worn spark igniter with incorrect gap, and gas valve solenoid failure. Cleaning the flame rod with fine steel wool or emery cloth fixes approximately 45% of cases. Flame rod part number 100074985 fits the RUR98iN and most current RU series models. The gas valve solenoid coils should read 30 to 80 ohms; out-of-range readings indicate valve failure. Reset after repair by pressing the power button twice.

RinnaiWaterheaterSeverity: highDifficulty: intermediate78% DIY Success

Time to Fix

20–90 min

Difficulty

intermediate

Parts Cost

$12 – $280

Tools Needed

Screwdriver set (Phillips and flathead), Fine steel wool or 400-grit emery cloth

Wrong code?

Not seeing 11 on your display?

Select what your appliance is actually doing and we'll take you to the right guide.

unit won't ignite

NavienE003

What Does the 11 Code Mean?

Three ignition attempts failed with no flame detected. Usually caused by a dirty flame rod, which is a 10-minute DIY fix. Gas supply issues and igniter problems account for most remaining cases.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Flame rod coated with oxide buildup preventing flame detection40%

Gas supply valve partially closed or gas meter issue24%

Spark igniter gap out of specification (should be 3 to 4mm)14%

Wiring connection to flame rod or igniter corroded12%

Gas valve solenoid coil failure10%

Symptoms You May Notice

Code 11 on controller display
Clicking ignition sound followed by unit shutdown
No hot water despite demand
Unit cycles on and off rapidly without heating
Faint gas smell near burner during ignition attempt

Can you reset a Rinnai waterheater to clear the 11 code?

After completing the repair, press the power button to turn the unit off, then press it again to turn it back on. Wait 2 minutes before opening a hot water tap to run a test cycle. If Code 11 returns after the first heating cycle, repeat step 3 and verify the flame rod connection is fully seated.

Tools Required for Diagnosis

Screwdriver set (Phillips and flathead)Fine steel wool or 400-grit emery clothMultimeterFeeler gauges or digital caliperFlashlight

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Verify gas supply is active

Verify gas supply is active. Turn on a gas stove burner or other appliance. If other gas appliances are also not working, the issue is upstream of the unit.

Confirm the gas shut-off valve on the supply line directly

Remove the burner access panel

Inspect the spark igniter tip

With power off, use a multimeter set to resistance (ohms) mode

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name	OEM Number	Estimated Price
Flame Rod (Flame Sensor)100074985 · $12–$25	100074985	$12 – $25
Spark Igniter AssemblyContact Rinnai with model number · $20–$35	Contact Rinnai with model number	$20 – $35
Gas Valve AssemblyContact Rinnai with model number · $150–$280	Contact Rinnai with model number	$150 – $280

Verify part fitment for your Rinnai model

Repair vs. Replace Calculator

Appliance Age (Years)7 Yrs

Labor Approach

Our Verdict

REPAIR

Estimated Cost: $146 (Parts) vs $1250 (New Machine)

Frequently Asked Questions

How do I clean the flame rod on a Rinnai water heater?

Turn off gas supply and allow the unit to cool. Remove the burner access panel (usually 2 to 4 screws on the front cover). Locate the flame rod, a slender metal probe near the burner assembly. Disconnect the lead wire, then use fine steel wool or 400-grit emery cloth to gently rub the rod until the oxide coating is removed and the metal is shiny. Reconnect the wire, reassemble, and test. The whole job typically takes 10 to 15 minutes.

Why does Rinnai Code 11 keep coming back after I reset it?

If Code 11 returns within minutes of resetting, the flame rod has not been cleaned or is physically damaged, the gas supply pressure is below the minimum operating threshold, or the gas valve solenoid is failing intermittently. Resetting without fixing the root cause will not resolve the problem. Work through the diagnostic steps above to identify which component is at fault.

What is the difference between Rinnai Code 11 and Code 12?

Code 11 means the unit never established a flame during any of its 3 ignition attempts. Code 12 means the unit successfully lit the burner but then the flame went out during operation. Both can involve the flame rod, but Code 12 points more toward gas pressure fluctuations or flow rate drops during operation rather than an ignition failure.

Can I replace the Rinnai flame rod myself?

Yes. Replacing the flame rod is a straightforward DIY repair that does not involve working on gas lines. Turn off gas supply, remove the access panel, disconnect the rod's lead wire, unscrew the rod (typically one screw), and install the replacement. Part 100074985 works on most current RU series models. Always turn off gas before opening the unit.

My Rinnai is only 2 years old. Why is it showing Code 11?

On a relatively new unit, Code 11 is most often caused by a gas supply interruption rather than a worn flame rod. Check whether the gas meter was serviced recently, whether an LP tank is running low, or whether the gas shutoff valve was accidentally bumped. If gas supply is confirmed normal, the flame rod may have a manufacturing defect or moisture from installation caused premature oxidation.

Related Rinnai Waterheater Error Codes

Code: HUBRinnai Tankless Water Heater Error Codes: Complete Guide Code: 12Rinnai Code 12: Flame Failure During Operation Code: 10Rinnai Code 10: No Gas Supply or Gas Valve Failure Code: RESETHow to Reset a Rinnai Tankless Water Heater: All Models Guide

Same Fix on Other Brands

Navien waterheaterE003: Navien E003 Error Code: Ignition Failure Fix for NPE and NCB Series

Models Known to Experience 11 Errors

This repair applies to most Rinnai waterheaters with this error code. Common model numbers include:

RUR98iN, RU199iN, RU98eN, V65iN, RL75iN, RU160iP

Last verified for technical accuracy on March 14, 2026