Key Takeaways
- Rinnai error code 11 means "No Ignition." Rinnai's own diagnostic document prints it that way. The unit tried to light, could not confirm a flame, and shut itself down on purpose.
- It is the number one tankless code we get called about. Over six years in Orange County it shows up on 97 jobs and 24 tracked calls, more than any other code.
- The usual answer is the flame rod, not a major component. On most of these visits we sand the flame rod and ignition rod clean, reseal, and the unit lights right back up.
- Budget the visit, not a parts list. Our tankless diagnostic runs $298 to $377, and about 95% of tankless diagnostic visits end in a repair rather than a new unit.
- Code 11 applies across the whole Rinnai range, which matters because 18 of Rinnai's 41 codes apply to only one product line.
Applies to: SENSEI models including RU199i, RU180i, RU160i, RU130i, RUR and CU, and non-SENSEI models including V53e, V65i, V75i, V94i, RL, RUCS, RUC, RU80i, RUR98i and C199i. Rinnai splits many codes by product series, which is why you find contradictory advice online. Code 11 is listed for both series, so it reads the same across the range.
If you are reading this, you have already looked the code up. Most people who reach us about a tankless unit arrive knowing roughly what they are dealing with. So let's skip that part and answer what people ask next.
What it means. Code 11 is Rinnai's "No Ignition" code. The unit ran its startup sequence, tried to light the burner, could not verify a flame was burning, and closed the gas valve. That is the safety system working, not the unit giving up.
What it usually costs. Our tankless diagnostic visit is $298 to $377, and the great majority of code 11 calls are resolved inside it. Full pricing in three tiers is further down.
How fast someone can get out. Call (949) 328-6002 and we can usually give you a scheduling window on the first call rather than making you wait for a callback.
Whether we work on your brand. We do. We install and service Noritz and Navien, and Rheem, Rinnai, Bradford White and A.O. Smith are all regulars in our service work. On Rinnai our history is lopsided in a useful way: 15 units sold, 96 Rinnai repair calls. Nearly every Rinnai we open was installed by somebody else.
The rest is detail, including a few things worth checking yourself first. Our water heater service page covers the repair side.
What code 11 is actually telling you.
Every ignition cycle is a short, precise sequence. You open a hot tap, the flow sensor notices water moving, the fan spins up, the gas valve opens, the igniter sparks, and then a separate component called the flame rod confirms there is fire in the chamber.
That last step is the one that matters. The flame rod is a thin metal probe sitting in the flame, and it works on an elegant piece of physics: a burning flame conducts a tiny electrical current, and the rod measures it. Current present, the board keeps the gas on. Current absent, the board assumes no flame, closes the valve within a couple of seconds, and posts code 11.
So two very different situations produce the same number. Either nothing lit, or something lit and the unit could not prove it. From the outside those look identical, and telling them apart is most of the diagnosis.
What it usually turns out to be in the field.
Code 11 is the single most common code we get called about: 97 jobs and 24 tracked calls over six years across Orange County. And on most of those visits the work is the same. We pull the flame rod and ignition rod, sand the deposits off, check the wiring and the ground, reassemble with a fresh seal, and the unit fires.
The rods sit in the flame. They collect carbon from combustion and mineral scale from the water side of the appliance, and a coated rod cannot read a current a clean rod reads easily. The flame is there. The unit simply cannot see it.
Rinnai has its own term for the related version of this, and we like it: a floating flame rod, meaning one that has worked loose in its mount rather than gone dirty. Rinnai's diagnostic document puts it in exactly those words, that a loose flame rod is called a floating flame rod and will result in a code 11. The igniter next to it has its own version of the same problem. Rinnai notes that if the electrode works loose, the tip can drop down and touch the burners, which creates a short or no spark at all. Either way the unit never establishes a flame the rod can read.
What people usually assume, and what it actually is.
Almost everyone who calls has a theory, and a good share of the time it is close. Three are worth gently correcting.
"The igniter is out." Usually not. The igniter and the flame rod are two different components doing two different jobs, and the flame rod is the dirty one far more often.
"It must be the control board." Boards do go, and we do replace them. But a board is the last thing we check, not the first. Checking it first is how a $298 visit becomes a $1,200 one.
"No hot water means the unit is done." The tankless units we service average about nine years old, with a clear cluster at the ten year mark. Nine is roughly when the maintenance a unit did or did not get starts showing up as codes, not the end of the road.
The California cause nobody expects.
Plenty of California homes have a seismic gas shutoff valve on the gas line. State law sets the certification standard and local jurisdictions decide when one is required, which is usually at new construction or a major remodel, so whether you have one depends on your city and your home's history. A small weighted mechanism inside drops and closes the line when it senses movement, and it does not only sense earthquakes. A heavy delivery truck, nearby construction or a solid bump can trip it.
When it trips, the gas stops. Your Rinnai runs its whole ignition sequence with no fuel behind it, sees no flame, and posts code 11. The unit is completely healthy. It has nothing to burn. We have found tripped earthquake valves behind more of these calls than you would believe, including on units somebody else had just replaced.
Walk to your gas meter and look for a second valve on the line, usually brass, separate from the main shutoff. If the indicator has shifted closed, it needs a reset. Anything past that visual check belongs to somebody who works on gas lines for a living.
The local factor: scale.
Orange County water runs roughly 8 to 19 grains per gallon depending on your district, firmly in the hard water range. Those are the districts' own published figures, not ours. Hard water leaves mineral deposits inside the heat exchanger and on everything downstream of combustion, including the rods. You can see it in our work mix: descaling is 45.1% of every tankless service job we perform.
Scale does not cause code 11 directly. It is the background condition that makes every other cause arrive sooner. A unit flushed annually since installation is a very different machine at year nine than one that has never been touched.
"No hot water since last night." What to check yourself.
Most people do not describe this as a water heater situation. They describe it as a shower. "It's the shower." "No hot water since last night." That is the right instinct, because the fixture is where you noticed it.
Here is what is safe to check yourself, in the order we would do it.
- Confirm it is the whole house. Run hot at a sink on another floor. If one fixture is cold and the rest are fine, a mixing valve at that fixture is more likely than the water heater.
- Check other gas appliances. Stove, dryer, furnace. If nothing gas powered runs, the issue is upstream of the water heater.
- Look at the earthquake valve. Covered above. Highest value thirty seconds on the list.
- Look at the vent termination from outside. Clear nests, webs, leaves or a dislodged cap you can see and reach safely. Do not reach inside the pipe.
- Power cycle once. Off, thirty seconds, on, open a hot tap. If the code returns, something persistent is behind it.
- Write down what you hear. Fan, clicks, a brief flame, how long before it quits. Genuinely useful to whoever comes out.
What we would not recommend doing yourself on a Rinnai is opening the combustion chamber to clean the rods. There is a specific reason, and it is the next section.
The detail almost nobody publishes: the gasket.
When a flame rod comes out of a Rinnai for cleaning or replacement, Rinnai's own repair procedure requires a new gasket on reassembly. The document says it in capital letters: have a replacement igniter and flame rod gasket on hand before removing these components, because once that seal has been disturbed the gasket MUST be replaced. Not optional, not a suggestion.
That gasket seals the combustion chamber, and a chamber that is not sealed correctly changes the air and exhaust behavior of the whole unit.
This is the honest reason we steer people away from a DIY rod cleaning on these units. Sanding a rod is not hard. The issue is that the correct procedure ends with a part most homeowners do not have on hand, and reusing the old one is not the same job.
Another plumber already said replace the Rinnai.
About a third of the people who reach us about a water heater have already had someone else look at it. The sentence we hear most is some version of "another plumber said it needs to be replaced, does that sound right to you?"
It might be right. Plenty of units genuinely reach the end of the road, and there are code 11 outcomes where a new unit is the better spend. We are not going to second-guess a diagnosis we did not see.
What we can offer is our own numbers. Roughly 95% of the tankless diagnostic visits we run end in a repair rather than a replacement. And on the component that most often ends the repair conversation, the heat exchanger, our record is thin: discussed on 146 completed tankless jobs over six years, actually replaced 11 times.
So a second opinion costs one visit, and if the first diagnosis was right you will hear that from us too. Age moves it most: a fifteen year old unit needing a board is a different conversation than a nine year old unit with a coated rod. Our water heater service starts with the diagnostic either way, and our guide to tank versus tankless water heaters covers the replacement math if you get there.
What a Rinnai code 11 costs.
We price this the way we invoice it, by visit and by named repair, not by part.
Cost Breakdown: Rinnai code 11 in Orange County, three tiers.
| Tier | What it is | Price |
| 1 | Tankless troubleshooting and diagnostic visit. Most code 11 calls end here. | **$298 to $377** |
| 2 | Flame rod cleaning during the visit | $195 to $279 |
| 2 | Ignition rod or flame rod replacement | $200 to $425 |
| 2 | Tankless flush and descale, if scale is the underlying condition | $255 to $316 |
| 2 | Control board, complete service, typically across two visits | about $1,200 |
| 2 | Control board install when you already have the part | $525 to $780 |
| 3 | Full tankless unit and installation, when repair is not the right call | **$5,950 to $8,975** |
Most code 11 calls end in tier one. That is not a sales line, it is what the invoice history shows. The rod cleaning happens inside the diagnostic visit.
The control board number needs its mechanism explained. About $1,200 is the complete job, not a line item. The board is never on the truck, so we call Rinnai technical support, work their process, then drive to a will call counter or wait on a shipment. That is usually two visits, which is why a smaller board line on an invoice and the $1,200 figure can both be true at once.
Venting corrections are quoted on site, because vent work runs from a screen at the termination to a full run replacement. Heat exchanger replacement is uncommon enough that we do not publish a range for it at all.
[SME: VERIFY] Eric, D-1 is still open. Is the $195 to $279 flame rod cleaning in addition to the $298 to $377 diagnostic, or included within it? Also confirm whether the $95 truck and dispatch line is additive, and whether it should be disclosed here.
For the broader picture, we have a full breakdown of water heater repair costs.
How the visit actually goes.
[SME: VERIFY] Eric, written as a composite of the pattern rather than one specific job. If you would rather anchor it to a real call, give me the address-free version and I will swap it in.
The call comes in the morning. No hot water since last night, and the homeowner already has the code. Nine times out of ten they lead with the shower, not the water heater.
I get out there and the first thing I do is not open the unit. I walk to the meter. If the earthquake valve is closed we are done in ten minutes, and I would rather learn that before a panel comes off.
Assuming gas is flowing, we open it and watch an ignition attempt through the view glass. Does it spark. Does it light at all. Does it light and then go straight back out. That last one is the tell, because it means the burner is fine and the unit could not see the flame. Rinnai's own procedure says the same thing: if you see a flame through the view glass and it goes out, the issue is in the flame rectification circuit or the gas system.
Then we pull the rods, and nine times out of ten they look exactly like a component that has sat in a flame in hard water country for nine years. Sand them to clean metal, check the harness and the ground, fresh gasket, test cycle, confirm it holds temperature at the tap. What you are paying for is somebody who checks the meter before the panel.
Keeping a Rinnai code 11 from coming back.
- Annual descaling. Given Orange County water this is the highest value thing you can do for a tankless unit, and it gives someone a reason to look at the rods and the vent once a year.
- A vent check twice a year. Thirty seconds outside, spring and fall.
- Pay attention to slow starts. Two or three attempts before it catches is the early version of a code 11.
- Locate your earthquake valve now, so it is a thirty second check later.
- Get eyes on the whole system periodically. A plumbing inspection covers the gas supply and venting side, where the causes that are not the rods tend to live.
FAQ.
My Rinnai shows code 11 and there is no hot water in the shower. Same thing?
Almost certainly. If the code is showing and no hot water reaches any fixture, the unit stopped its ignition cycle. Check a second fixture on another floor first, because if one shower is cold and the rest of the house is fine, that points at the fixture rather than the water heater.
How much does it cost to fix Rinnai error code 11?
Our tankless diagnostic runs $298 to $377 and the majority of code 11 calls are resolved inside it. Named repairs run $195 to $425 for flame rod cleaning or replacement and about $1,200 for a complete control board service across two visits. Full replacement, when that is genuinely the right call, is $5,950 to $8,975.
Can I reset Rinnai error code 11 myself?
Worth trying. Turn the unit off, wait thirty seconds, turn it back on and open a hot tap. If it returns, something persistent is behind it, and repeated resets will not resolve a coated flame rod or a closed gas valve.
Is Rinnai code 11 dangerous?
No. Code 11 is the unit declining to run because it could not confirm a flame, which is exactly what you want a safety control to do. The separate situation that is urgent is a gas smell: leave the house first, then call your gas utility or an emergency plumber.
Does code 11 mean the same thing on every Rinnai model?
Yes, and that is worth saying plainly because it is not true of every Rinnai code. Eighteen of the forty one codes in Rinnai's diagnostic document apply to only one product line. Code 11 is listed for both series, so it reads the same across SENSEI models like the RU199i and RU160i and across non-SENSEI models like the V65i, RL and RUC series.
How is code 11 different from Rinnai code 61?
Different moment in the same sequence. Code 11 means the unit could not establish and confirm a flame at startup, while code 61 points at the combustion fan. Seeing both at different times usually points at venting or gas supply.
Do you work on Rinnai, or only the brands you sell?
Both. We install and service Noritz and Navien, and Rheem, Rinnai, Bradford White and A.O. Smith are all regulars in our water heater service work. On Rinnai the numbers are lopsided: 15 units sold in our history, 96 Rinnai repair calls. Our tankless brand comparison covers the buying side.
Is Rinnai code 11 the same as Noritz code 11?
Close cousins, not twins. Both brands use 11 for an ignition related shutdown, which is why our Noritz code 11 guide will feel familiar. The differences are in the hardware and in each manufacturer's specified repair procedure.
The bottom line.
Rinnai error code 11 means No Ignition. The unit tried to light, could not confirm a flame, and shut down rather than keep sending gas to a burner it could not verify. That is the appliance protecting your house.
In six years of Orange County service work this is the code we get called about more than any other, and the answer is usually a flame rod carrying enough carbon and mineral scale that it can no longer read the flame in front of it. Sand it, seal it correctly with a fresh gasket, and the unit goes back to work.
Before you call anyone, confirm other gas appliances are running, look at the earthquake valve at your meter, and try one power cycle. Five minutes, and they resolve a real share of these.
If the code comes back, we would recommend a diagnostic before any replacement conversation, because the odds strongly favor a repair. Our water heater service covers Rinnai, Noritz, Navien, Rheem, Bradford White and A.O. Smith across Orange County. Call (949) 328-6002 or schedule a visit and tell us the code.
Written by [Eric Olson](/about/eric-olson), Licensed Master Plumber, Olson Superior Plumbing, Orange County, CA. Code meanings, model applicability and repair procedure verified against Rinnai Document 100000652, "Troubleshooting Tankless Water Heater Diagnostic Codes." Field figures come from Olson Superior's own service records. The 8 to 19 grains per gallon hardness range is a municipal water-district figure, not ours.
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