Noritz Code 11: Ignition Failure

The Short Answer: Noritz code 11 is ignition failure: the board tried to light, never proved flame, and locked out. It is not a Rinnai air code and not a tank LED count. Photograph it. Confirm the cock and LP. Reset once. Do not measure manifold pressure yourself. Do not keep cycling a flooded burner. Ice-cold with no digit is Noritz not working.

Search Intent & The Real Problem

The remote (RC-7651M / RC-9018-class) or the PCB 7-seg says 11. The shower died. Google mixed a Rheem Paloma 11, a Honeywell flash count, and a Rinnai 10 into one stew. On Noritz NRC, EZ, NR, NRCP, and NCC gas tankless, 11 is the ignition-failure lockout: spark ran, flame never proved. 12 is the sister — it lit, then lost flame (same split as Takagi 111 and Rheem 11). 14 is thermal fuse. A packed inlet screen that never calls for fire often shows no 11 at all.

What other guides get wrong

They paste a Rinnai 10/11/12 table onto a Noritz. Noritz fan and combustion faults are 61 / 90 / 99, not 10. They tell you to reset until it fires. Ten resets glaze the igniter and flood the chamber. They send homeowners at a manometer. They “fix” 11 by descaling first — scale is 14/16. And they skip a closed appliance cock and a 1/2” flex on a 180–199 kBTU burner, so you buy a flame rod for a starvation install.

Step-by-Step Troubleshooting

Step 1: Photograph 11 vs 12 vs 14 — then stop guessing

• What to look for: Digits before you kill power. Rating plate: NRC1111, EZ98/EZ111, NR98OD, NRCP, NCC199, Quick-Connect pair. Indoor PVC/PP vs outdoor rain cap. A bang on a late light is delayed ignition — loud bang — shut it down, not a second trial.
• Required tools: Phone photo of the code and the plate. No wrenches.

If there is no code and it simply passes cold water, you may have no flow call, not an 11. Packed screen and closed isolation never ask the burner to light — no water flow.

Step 2: Gas cock, other appliances, LP — no manometer

• What to look for: Appliance shutoff handle parallel to the pipe (open). Stove and furnace lighting. LP bottles not empty; a first-stage regulator frosting on a 20°F morning will 11 a Noritz that was fine in July. 1/2” CSST or flex on a 199 kBTU chassis is a starvation install — the range lights, this burner never proves. New meter relight in the last day can be air in the line. That is a licensed purge and leak test, not a union crack. No gas at other appliances is not getting gas, not a board. Fuel DIP or orifice set to the wrong gas after a move is a licensed correction.
• Required tools: Eyes on the cock and the flex. No fittings wrenches.

Inlet and manifold pressure are licensed (NG often ~3.5–7 in. w.c. / LP ~10–11 in. w.c. — confirm the rating plate, never by ear). A thermocouple millivolt ritual does not apply to this box.

Step 3: Igniter, sight glass, one trial

• What to look for: Cover on. One hot-water call. Listen: fan, then spark, then silence and 11. No spark at all: igniter, high-voltage lead, or PCB — still not a homeowner gas-valve swap. Spark with a dark burner: fuel never arrived (cock, valve, or empty LP). Brief yellow puff then 11: delayed light or a wet/sooted burner after rain in the cap. Do not run it with the cover off “to see better.”
• Required tools: Ears and eyes. One trial.

A light wipe on a cool flame rod is the most a homeowner should do. Do not sandpaper it into a needle. Microamp flame current is a licensed reading. Repeated 11 with a wet cabinet is a leak first — Noritz from the bottom. Sister Paloma-class 11 physics: Rheem tankless flashing 11 is a different brand with the same “never lit” logic.

Step 4: Vent, wind, and condensate that starve the trial

• What to look for: Outdoor NR/NRC on a windward wall, missing rain cap, snow over the flue. Indoor NRC/EZ: termination too close to a soffit, long concentric run mashed shut, or a condensate trap full so the fan never proves a stable fire. 61/90/99 should have shown for a dead fan; some boards still throw 11 when the trial never sees flame in a bad flue. Bird nest, dryer blowing into the same corner, vinyl intake crushed. Condensing trap overflow that wet the board is condensate physics — power off.
• Required tools: Eyes on the cap from the ground. Do not garden-hose the vent.

Clear the exterior. Do not foil a vent joint. A power-vent tank with a dead blower is not a Noritz 11 — blower not working.

Step 5: One reset after the cause — then hire it

• What to look for: Cause addressed (cock open, cap clear, LP not frozen). Power off 10–30 seconds, or remote Off then On. Unit fires, holds flame, no 11 on the next shower. Same 11 on the next call is the end of DIY. Do not descale an 11 as step one. Do not hold a tripped breaker On. After a utility outage start at dead after power outage physics — GFCI and freeze circuit — not a tenth reset. Flame-loss after a successful light is 12, closer to Rinnai 12 than to this 11.
• Required tools: Your hand on the switch. No paperclip in the PCB.

Need it dark while you wait? Apartment shutoff. Closet odor now is leave — closet smells like gas.

When DIY Ends: Calling a Licensed Pro

Stop at gas odor, delayed-ignition bangs, a 13, an 11 that returns after one reset, a wet board, a silent fan, and any gas-pressure or gas-valve work. You may photograph the code, confirm the shutoff, look at the termination, rinse an inlet screen with water isolated, and power-cycle once. Combustion, manometer, igniter or flame-rod replacement inside the burner, and PCB work are licensed. Noritz will not smile on a rod you reset through a flooded burner all weekend.

Frequently Asked Questions

Q: What does Noritz water heater code 11 mean? A: Ignition failure — no proven flame in the trial. 12 is flame loss after it lit. 14/16 are overheat/scale. 61/90/99 are fan and combustion. A gas-tank LED flash count is a different chart.

Q: How do I reset a Noritz code 11? A: Photograph the code, fix the obvious cause (gas cock, LP, wind at the cap), then power off 10–30 seconds or toggle the remote. One reset. An 11 that returns is a licensed diagnosis, not a reset schedule.

Q: Can I check gas pressure on a Noritz 11 myself? A: No. Confirm the shutoff and that other appliances light. Inlet and manifold pressure are a licensed manometer job. Do not loosen fittings to “bleed air.”