Noritz NR98 & NR111 Code 72
Flame rod circuit fault. The unit is detecting a flame when there should not be one. Noritz measures the current from the flame rod with no flame present and checks for a ground fault. It is the reverse of code 12: not failing to see a real flame, but seeing one that is not there. This range has no external CO alarm interlock — that is code 13 on the EZ and NCC199CDV table, and it does not exist here. A false flame signal on an NR98 or NR111 is the flame rod circuit and nothing else.
Also displayed as: F72
Call a proThe verdict
Call a licensed plumber
A false flame signal is a safety fault, because the logic that decides whether it is safe to open the gas valves depends on that reading being honest.
Typical cost: $150–$700
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 NR98 & NR111 — not averaged across the brand.
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 exact series.
What you can safely check
Before anything else: if you smell gas, stop here, leave, and call your gas utility.
- Cut the power for a minute and restore it.
- If 72 returns, switch the unit off and leave it off.
- Call a licensed professional — a ground fault is one of the two named causes and it needs measuring.
Code 72 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 NR98 & NR111 code points at flame detection 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: