Noritz Code 11: Ignition Failure on NRC and EZ Models

Noritz code 11 means ignition failure: the heater tried to light and could not. Confirm the gas valve is fully open, clear the code with the power button or by closing and reopening the hot tap, and contact Noritz or a gas pro if 11 returns.

The manuals never say “no ignition”. The NR71, NR66 and NR50 owner’s guide and the NRC111DV and NRC111OD guide (SBB80HS-2) print “Ignition error”, while the EZ111DV, EZ98DV, EZ71DV, NRCR111DV and NRCR92DV guide (SBB81HC, Rev. 01/24) prints “Ignition failure”. That guide also separates a heater that “does not attempt to ignite when water is running” from one that “attempts to ignite but fails”. Code 11 belongs to the second group. A heater that never tries points to water flow instead (0.4 GPM minimum activation on the EZ series), which our tankless troubleshooting guide covers by symptom.

Which Noritz code is it: 11, or 10, 12, 14, 16, 29, 90 or 99?

Code 11 is the failed start; the other seven report lost flame, heat, drainage or combustion faults. Meanings come from Noritz’s NCC199 and NRC111 service list unless a family is named, because no single owner’s guide prints all eight.

Read the table by timing first. Code 11 is a start that failed, while code 12 is flame lost during operation, and the service list gives both the same pro checks. Codes 10, 90 and 99 need the power cut on NCC199 and NRC111 heaters, a step the list does not attach to 11. Codes 10, 12, 14 and 16 appear in none of the owner’s guides read here, and those guides send every unlisted number to Noritz: contact them if “any other error code appears”.

Did code 11 appear right after draining, a gas shutoff or a new install?

Noritz expects code 11 during manual draining, so a code that shows up mid-drain is not a fault. The EZ111DV, NRC111 and NRCP guides all say an 11 may appear while a hot fixture runs for more than 2 minutes with the gas valve closed (2 minutes per heater on multi-unit systems), that this is not a malfunction, and that you should leave the power on. If 11 stays after you restart, look first at the gas supply valve, which step 5 of the EZ guide’s “Turning the Water Heater Back On” reopens.

New installs and recent gas work have a second documented cause: air in the line. The EZ and NRC98 and NRC83 guides answer “attempts to ignite but fails” with a reset, a retry and a warning that there may be air in the gas line. The NRC661-DV installation manual tells installers to repeat the test “until the air in the gas piping is bled out”. On a quick connect pair, the N-084M manual calls for pressing the power button off and on 2 to 3 times if 11 or F11 flashes at first firing.

How do you clear Noritz code 11, and is there a reset button?

None of the six Noritz owner manuals read for this page names a separate reset button for code 11. You clear it with the power button, a power switch or the hot water fixture, in the order your family’s document gives.

The NR, NRC and EZ guides share one test: if the flashing number does not return, the problem is solved.

Noritz code 11 fix order, from gas valve to phone call

Work from the gas smell check to the phone call in 6 steps, and stop at the first one that ends in a professional.

1. Smell gas? Leave the building first. The EZ111DV guide says do not light any appliance, touch an electrical switch or use a phone in the building. From a neighbor’s phone or outside, call the gas supplier, or 911 if you cannot reach it.
2. Turn the gas valve by hand only. Open it fully. If it will not turn by hand, the EZ guide says not to force or repair it. Call a qualified technician.
3. Test the supply. Light a stove or another gas device, the test the EZ guide suggests for both a meter shutoff and an LP tank. If nothing lights, the fault is upstream of the heater, so call the gas utility or propane supplier.
4. Clear the code once using your family’s method above, then open a hot tap fully. EZ models need 0.4 GPM to activate.
5. Look at both vents from outside the cabinet. Noritz’s own code 11 advice names an obstructed exhaust vent. EZ owners drawing combustion air indoors should also check the air supply vent described on page 20 of the guide.
6. Code back? Call. Noritz Technical Support is 1-866-766-7489. Have the model from the rating plate, the purchase date and the exact blinking code ready.

Where can the gas and ignition path fail on a Noritz heater?

Code 11 can trace to any of 4 paths: gas, spark, flame signal or air. Noritz’s seven common codes article names insufficient gas, insufficient air flow and debris on the ignition plug, and its help center Error Code 11 article adds that an 11 can occur when the unit lights but fails to detect ignition through the flame rod. That article uses the burner’s sight glass to tell the two apart, a flame seen for a moment means detection, not lighting, and it says gas troubleshooting should be left to a professional. Only the marked boxes below are owner checks.

Ask the technician for these by name, each from the NCC199 and NRC111 service list, with a manometer, voltmeter and screwdriver as the tools: incoming gas pressure, gas type, a clean ignition plug and flame rod, venting, and unit grounding. Noritz’s documents differ on cleaning material. The service list says green scrub pad, no sandpaper or emery cloth, while the help center article says the rough side of a sponge or a dollar bill. Neither is an owner step, because the EZ111DV guide reserves service for a qualified installer, service agency or the gas supplier.

On an NRC661-DV the pressure test is a licensed gas pro’s job, not an owner step, and it has a set method: the pro removes the 9/32 in. hex head screw from the tap on the gas inlet, connects a manometer with silicone tube, opens at least 2 fixtures and holds the maximum manifold pressure button on the circuit board. The manual’s supply limits are 4 to 10.5 in. WC on natural gas and 8 to 14 in. WC on LP, with all gas appliances running, and it separately asks for 5 in. WC on natural gas at every appliance in the system. Have the tech confirm limits for your model.

Pressure that sags only at full demand points to the piping or regulator. An EZ111DV can draw 199,900 Btu/h through its 3/4 in. NPT gas inlet, so have the run checked against a gas pipe sizing chart. A venting obstruction on the service list’s code 11 checklist is a separate job, governed by water heater venting rules and the heater’s manual.

How many resets does Noritz allow before code 11 needs service?

Noritz publishes no reset count for owners: the NR, NRC and EZ guides all say to contact Noritz when “an error code is indicated again after the above actions were followed”. The closest thing to a number is the NRCP guide, where Er:11 means ignition has already failed 10 times and the heater enters a hard lockout, a state its guide reserves for conditions that prevent safe operation. The 2 to 3 presses in the N-084M manual apply to a quick connect first firing, not to a heater that worked yesterday.

Noritz’s seven codes article is stricter than its manuals: check that the gas is on, then call a licensed contractor. Our reading of those documents: one reset, a retry only after gas work that could have left air in the line, and service when 11 comes back. If that visit lands on an older heater, compare the repair quote with how long water heaters last before approving parts.