Noritz tankless water heater code 12
Flame rod does not detect flame. Code 12 means the same thing on all 5 Noritz series documented here — but the fix, and what it costs, is still worth reading for your exact unit.
What code 12 means on each Noritz series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| EZ Series & NCC199CDV | Flame rod does not detect flame | Call a pro | $0–$800 |
| NCC199 & NRC111 | Flame rod does not detect flame | Call a pro | $0–$800 |
| NR50, NR66 & NR71 | Flame rod does not detect flame | Call a pro | $0–$800 |
| NR98 & NR111 | Flame rod does not detect flame | Call a pro | $0–$800 |
| NRC Series | Flame rod does not detect flame | Call a pro | $0–$800 |
Each row opens the full page for that generation. We hold manuals for EZ Series & NCC199CDV, NCC199 & NRC111, NR50, NR66 & NR71, NR98 & NR111 and NRC Series, and each one gets its own reading of code 12 — what Noritz documents, what you can safely check yourself, and what the repair should cost.
What each manual actually says
The table above compares 5 series in four columns, which is enough to route you and not enough to explain anything. This is the Noritz wording behind each row, one entry per manual, so you can see where the 5 readings of code 12 agree and where they part company.
EZ Series & NCC199CDV — Flame rod does not detect flame
The unit lit and lost the flame, or could not confirm it. Noritz lists accidental extinction of the flame, abnormal combustion, the gas valve, the flame rod, and the ground — especially on the circuit board. Where 11 is never starting, 12 is not staying lit. This range has an external CO alarm interlock at code 13 that no other Noritz table on this site carries. If a 12 is appearing alongside anything from that interlock, stop treating it as a flame-detection fault and read the code 13 page first.
NCC199 & NRC111 — Flame rod does not detect flame
The unit lit and lost the flame, or could not confirm it. Noritz lists accidental extinction of the flame, abnormal combustion, the gas solenoid valves, the flame rod, and the ground — especially on the circuit board.
NR50, NR66 & NR71 — Flame rod does not detect flame
The unit lit and lost the flame, or could not confirm it. Noritz lists accidental extinction of the flame, abnormal combustion, the gas solenoid valves, the flame rod, and the ground — especially on the circuit board. Continuous flashing on a unit with no remote controller. On an NR71 or N-0631S with no controller you will not see a 12 at all, only the light flashing continuously — the same signal 10, 11, 59 and 90 produce. Distinguishing them without a controller means working through what the unit is actually doing, not what it is displaying.
NR98 & NR111 — Flame rod does not detect flame
The unit lit and lost the flame, or could not confirm it. Noritz lists accidental extinction of the flame, abnormal combustion, the gas solenoid valves, the flame rod, and the ground — especially on the circuit board. Worth knowing on this range: the table it belongs to also carries code 41 for the flow sensor, which the NCC199 and NRC111 table does not. A unit that lights and then loses flame at low draw is worth checking against that number too.
NRC Series — Flame rod does not detect flame
The unit lit and then lost the flame, or could not confirm it was there. Noritz's list is accidental extinction of the flame, abnormal combustion, the gas solenoid valves, the flame rod itself, and an improper connection of the earth cable. Where code 11 is about never starting, 12 is about not staying lit.
Does it matter which Noritz you have?
EZ Series & NCC199CDV, NCC199 & NRC111, NR50, NR66 & NR71, NR98 & NR111 and NRC Series all route code 12 the same way: a professional, at $0–$800. That makes it one of the Noritz numbers you can act on before working out which unit you own.
What to check first, whatever your series
These checks are on the manufacturer's list for every Noritz series that reports code 12, so they are safe to work through before you have identified your exact unit. They also cost nothing.
- Check gas is on at the heater and the meter.
- Call a licensed professional.
That is 2 of the 4 checks documented for code 12. The rest differ by generation, so if none of those explains it, go to your own series above.
Which Noritz do you have?
On the 5 series that report code 12, the model number on the rating label starts EZ, NCC, GQ, N and NRC — match yours against the 43 listed below. You can also use the full model-number decoder.
Where this comes from
Source: Noritz Service Manual — NRC663 FSV, EZ98DV, EZ111DV, NCC199CDV (Rev. Oct 2017) (p. 32), read Sep 2026 — the manufacturer's own documentation for this Noritz range.
Source: Noritz Service Manual — NR50 / NR66 / NR71 / NR98 / NCC199 / NRC111 / NR111 / NC380 (Rev. July 2011) (p. 55), read Sep 2026 — the manufacturer's own documentation for this Noritz range.
Source: Noritz Service Manual — NR50 / NR66 / NR71 / NR98 / NCC199 / NRC111 / NR111 / NC380 (Rev. July 2011) (p. 54), read Sep 2026 — the manufacturer's own documentation for this Noritz range.
Source: Noritz Service Manual — NR50 / NR66 / NR71 / NR98 / NCC199 / NRC111 / NR111 / NC380 (Rev. July 2011) (p. 56), read Sep 2026 — the manufacturer's own documentation for this Noritz range.
Source: Noritz Service Manual — NR501-OD, NR662-OD, NRC661, NRC711 (Rev. Dec 2013) (p. 28), read Sep 2026 — the manufacturer's own documentation for this Noritz range.
The same number on other brands
Code 12 is not a standard across the industry — every manufacturer publishes its own table. If your unit is not a Noritz, this number means something else entirely:
Parts, guides and symptoms behind code 12
Code 12 on these 5 Noritz series points at 2 parts and 3 symptoms, each named by the manufacturer's own procedure for this code.