Noritz NRC Series Code 35
Exhaust thermistor fault. The sensor in the exhaust is out of range. Noritz gives it four display-window codes — two pairs for open circuit and short — and the procedure is resistance and connection, the same as the other thermistors. What makes this one different is where it sits: in the exhaust stream, where the appliance watches for a flue temperature that says combustion has gone wrong.
Also displayed as: 351, 352, 353, 354
Call a proThe verdict
Call a licensed plumber
The part is as cheap as the other thermistors, but this one is in the flue, and while it is unreliable the unit has lost the input it uses to detect an overheating exhaust. Have it done rather than deferred.
Typical cost: $150–$500
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 NRC Series — not averaged across the brand.
Source: Noritz Service Manual — NR501-OD, NR662-OD, NRC661, NRC711 (Rev. Dec 2013) (p. 28), 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 the display-window code — Noritz uses 351 and 353 for one condition, 352 and 354 for the other.
- Call a licensed professional. The sensor sits in the exhaust and the checks around it are combustion checks.
Frequently asked questions
Why is this a professional job when codes 30 to 33 are not?
Because of where the sensor lives. Codes 30 to 33 are air and water sensors; code 35 is in the exhaust stream, and the same part failing there means the appliance can no longer see a flue temperature going out of range. It is the input behind code 94.
Code 35 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
4 other Noritz NRC Series codes point at a thermistor 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: