Noritz EZ Series & NCC199CDV Code 16
Abnormally high output temperature. The water leaving the unit is too hot. Noritz measures the hot water thermistor, then checks the offset pressure of the gas valve, then the gas type. As with code 15, the first cause is a measurement problem and the other two are combustion problems.
Also displayed as: F16
Call a proThe verdict
Call a licensed plumber
Turn the set temperature down and treat scalding as a live risk until this is fixed. Gas valve offset pressure needs a manometer, so the diagnosis is not a homeowner job even though the symptom is obvious.
Typical cost: $200–$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 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.
- Turn the set temperature down at the controller and warn the household before anyone runs a tap.
- Note whether the unit has ever been converted between gas types.
- Call a licensed professional.
Code 16 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: