Noritz NR98 & NR111 Code 33
Heat exchanger thermistor fault. The heat exchanger sensor is out of range. Noritz measures its resistance, checks for an open or short circuit, and checks the connection. This range has one heat exchanger thermistor. The EZ and NCC199CDV range has two — an inlet at 36 and an outlet at 33 — so a code 33 page written for those models is describing a different sensor position on a different appliance.
Also displayed as: F33
Part replacementThe verdict
Replace a part
Cheap sensor, service call to reach it. Ask about scale while the unit is open — this range has a dedicated code for a scaled heat exchanger at 59, and a sensor sitting on a furred one reads late.
Typical cost: $120–$450
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 NR98 & NR111 — not averaged across the brand.
Source: Noritz Service Manual — NR50 / NR66 / NR71 / NR98 / NCC199 / NRC111 / NR111 / NC380 (Rev. July 2011) (p. 56), read Sep 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
- Ask the technician to check the heat exchanger for scale while it is open.
- Book a service call.
Code 33 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
3 other Noritz NR98 & NR111 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: