Noritz NCC199 & NRC111 Code 73
Circuit board setting fault. The board's configuration is wrong or has been changed. Noritz checks the maintenance writers, the board for damage, the DIP switch, and the "control switch connector" — giving the high elevation connector as the example. Elevation and vent settings determine how the appliance burns gas, so these are combustion settings rather than preferences.
Also displayed as: F73
Call a proThe verdict
Call a licensed plumber
This usually appears right after someone has been inside the unit or swapped a board. Correcting it is professional work even though the physical act is moving a switch.
Typical cost: $100–$800
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 NCC199 & NRC111 — not averaged across the brand.
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 exact series.
What you can safely check
Before anything else: if you smell gas, stop here, leave, and call your gas utility.
- Think back to any recent work on the heater or its venting and mention it when you book.
- Do not open the unit to change switch positions yourself — these control combustion.
- Call a licensed professional.
Code 73 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 NCC199 & NRC111 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: