Noritz tankless water heater code 16
Abnormally high output temperature. Code 16 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 16 means on each Noritz series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| EZ Series & NCC199CDV | Abnormally high output temperature | Call a pro | $200–$900 |
| NCC199 & NRC111 | Abnormally high output temperature | Call a pro | $200–$900 |
| NR50, NR66 & NR71 | Abnormally high output temperature | Call a pro | $200–$900 |
| NR98 & NR111 | Abnormally high output temperature | Call a pro | $200–$900 |
| NRC Series | Abnormally high output temperature | Call a pro | $200–$900 |
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 16 — 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 16 agree and where they part company.
EZ Series & NCC199CDV — Abnormally high output temperature
The water leaving the unit is too hot. Noritz measures the hot water thermistor, then checks the offset pressure of the gas valve, then the gas type. As with code 15, the first cause is a measurement problem and the other two are combustion problems.
NCC199 & NRC111 — Abnormally high output temperature
The water leaving the unit is too hot. Noritz measures the resistance of the outlet thermistor and then checks the gas proportioning valve — one cause is a measurement problem, the other is the appliance really overfiring.
NR50, NR66 & NR71 — Abnormally high output temperature
The water leaving the unit is too hot. Noritz measures the resistance of the outlet thermistor and then checks for proportional gas valve trouble — one cause is a measurement problem, the other is the appliance really overfiring. Three flashes on an NR71 or N-0631S without a remote controller. This generation has no bypass or mixing valve to blame for an overshoot — the water servo codes 65 and 66 that later Noritz ranges carry do not exist on this table. That leaves the outlet sensor and the gas valve, which is exactly the two-cause list Noritz gives.
NR98 & NR111 — Abnormally high output temperature
The water leaving the unit is too hot. Noritz measures the resistance of the outlet thermistor and then checks for proportional gas valve trouble. One cause is a measurement problem, the other is the appliance genuinely overfiring. This table names the part a proportional gas valve where the NCC199 and NRC111 table calls the same component a gas proportioning valve. It is the same valve and the same check; the difference matters only when someone is ordering a part from the wrong page.
NRC Series — Abnormally high output temperature
The water leaving the unit is hotter than it should be. Noritz checks three things in order: the resistance of the hot water thermistor, the gas proportioning valve, and the manifold pressure. The first would mean the unit is measuring wrongly; the second and third mean it really is overfiring, which is a combustion problem rather than a measurement one.
Does it matter which Noritz you have?
EZ Series & NCC199CDV, NCC199 & NRC111, NR50, NR66 & NR71, NR98 & NR111 and NRC Series all route code 16 the same way: a professional, at $200–$900. That makes it one of the Noritz numbers you can act on before working out which unit you own.
Which Noritz do you have?
On the 5 series that report code 16, 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 16 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 16
Code 16 on these 5 Noritz series points at 3 parts and 2 symptoms, each named by the manufacturer's own procedure for this code.