Noritz EZ Series & NCC199CDV Code 73
Circuit board setting fault. The board's configuration is wrong or has just been changed. Noritz checks the maintenance writers, the board itself for damage, and the DIP switch settings — giving exhaust type and vent length as the examples. The remark explains the most common trigger: this error is displayed when switching the dip switch with the power on.
Also displayed as: F73
Call a proThe verdict
Call a licensed plumber
If someone has just been inside the unit, this is almost certainly why. The settings encode exhaust type and vent length, which determine how the appliance burns gas, so correcting them is professional work — and Noritz's note says the switches should not be moved with the power on.
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 EZ Series & NCC199CDV — not averaged across the brand.
Source: Noritz Service Manual — NRC663 FSV, EZ98DV, EZ111DV, NCC199CDV (Rev. Oct 2017) (p. 32), 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 whether anyone has worked on the heater or its venting recently, and say so when you book.
- Do not open the unit to change settings 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 EZ Series & NCC199CDV 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: