Noritz EZ Series & NCC199CDV Code 65
Main water servo fault. The main water servo is not functioning. This is the motorised valve that meters how much water goes through the heat exchanger, and it is how the appliance holds your set temperature at varying flow. Noritz checks that the servo is functioning and looks for an improper connection at the valve, and notes that the power has to be cycled to clear the code.
Also displayed as: F65
Part replacementThe verdict
Replace a part
Cycle the power first — Noritz's own remark says that is the reset, and a servo that stuck once may free itself. If it comes back it is the valve or its wiring, which is a service call and a moderately priced part.
Typical cost: $0–$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 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
- Switch the unit off at the breaker, wait a minute, and switch it back on.
- Run a hot tap and see whether the code returns.
- If it returns, book a service call — Noritz's two causes are both at the valve.
Code 65 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: