Noritz EZ Series & NCC199CDV Code 94
Exhaust temperature too high. The flue is running hotter than it should. Noritz's check is a single line — check for abnormal combustion, pointing at the exhaust thermistor — and the remark is that power must be cycled to clear it.
Also displayed as: F94
Call a proThe verdict
Call a licensed plumber
A hot flue usually means the heat exchanger is no longer moving heat into the water, which means scale, or that combustion has drifted. Both get worse, and the second puts heat into vent materials sized for a cooler exhaust.
Typical cost: $200–$1,000
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.
- Note when the unit was last flushed.
- Call a licensed professional rather than resetting it repeatedly to get through the week.
Code 94 on other Noritz series
Other Noritz series report code 94 under the same fault name, but each manual is transcribed separately and they do not read alike:
Don't confuse this with
One other Noritz EZ Series & NCC199CDV code points at the exhaust path 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: