Noritz NR50, NR66 & NR71 Code 70
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.
Also displayed as: 5 flashes
Part replacementThe verdict
Replace a part
Cut the power for a minute and restore it. A board that faults once on a supply glitch may not fault again; if it comes back, it is the most expensive single part in the appliance — and on a heater of this age, worth weighing against replacement.
Typical cost: $0–$900
US estimate for parts and labor. Prices vary by region and by who does the work — see how we estimate costs.
What the manual says
The meaning above is transcribed from the manufacturer's diagnostic documentation for the NR50, NR66 & NR71 — not averaged across the brand.
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 exact series.
What you can safely check
- Switch off at the breaker, wait a full minute, switch back on.
- Run a hot tap and see whether the code returns.
- If it returns, book a service call — and ask what a board costs against the value of the unit before agreeing to it.
Code 70 on other Noritz series
The same code number can mean something different on another series — make sure you're reading the page for your exact unit:
Don't confuse this with
One other Noritz NR50, NR66 & NR71 code points at the circuit board too. They are different components in different places, and ordering a part against the wrong one is the most common way this fault gets expensive: