Noritz tankless water heater code 70
Circuit board fault. Code 70 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 70 means on each Noritz series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| EZ Series & NCC199CDV | Circuit board fault | Part replacement | $0–$900 |
| NCC199 & NRC111 | Circuit board fault | Part replacement | $0–$900 |
| NR50, NR66 & NR71 | Circuit board fault | Part replacement | $0–$900 |
| NR98 & NR111 | Circuit board fault | Part replacement | $0–$900 |
| NRC Series | Circuit board fault | Part replacement | $0–$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 70 — 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 70 agree and where they part company.
EZ Series & NCC199CDV — Circuit board fault
The circuit board has reported a fault in itself. Noritz's entire diagnosis column is two words — circuit board failure — and the remark is that power must be disconnected and reconnected to clear it.
NCC199 & NRC111 — Circuit board fault
The circuit board has reported a fault in itself. Noritz's entire diagnosis column is two words: circuit board failure.
NR50, NR66 & NR71 — Circuit board fault
The circuit board has reported a fault in itself. Noritz's entire diagnosis column is two words: circuit board failure. Five flashes on an NR71 or N-0631S with no remote controller. On a heater of this age the arithmetic matters more than the diagnosis. These units date from the early 2010s and a circuit board is the most expensive part in them, so a returning 70 is the point at which repair and replacement are worth comparing honestly.
NR98 & NR111 — Circuit board fault
The circuit board has reported a fault in itself. Noritz's entire diagnosis column is two words: circuit board failure. A board on this range has to be set for a model list spanning residential NR98 units and commercial ASME units, so a replacement is not a like-for-like swap — expect code 73, the setting fault, to follow a board change until the switches are configured.
NRC Series — Circuit board fault
The circuit board has reported a fault in itself. Noritz's entire diagnosis column for this code is two words — circuit board failure — and the remark is that power has to be disconnected and reconnected to clear it. The display window appends a digit from 1 to 9 identifying which internal check failed.
Does it matter which Noritz you have?
EZ Series & NCC199CDV, NCC199 & NRC111, NR50, NR66 & NR71, NR98 & NR111 and NRC Series all route code 70 the same way: a replacement part, at $0–$900. 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 70, so they are safe to work through before you have identified your exact unit. They also cost nothing.
- Run a hot tap and see whether the code returns.
That is 1 of the 4 checks documented for code 70. 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 70, 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 70 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 70
Code 70 on these 5 Noritz series points at 1 guide, 1 part and 2 symptoms, each named by the manufacturer's own procedure for this code.