Noritz NRC Series Code 30
Air thermistor fault. The sensor reading the incoming air temperature is out of range. Noritz's procedure is to measure its resistance and check the connection, looking specifically for an open circuit or a short — the two display-window codes separate those cases for a technician.
Also displayed as: 301, 302
Part replacementThe verdict
Replace a part
A cheap sensor and a short job, but it is inside the cabinet of a gas appliance, so it is a service call rather than a homeowner swap. Nothing about the fault is dangerous — the unit has simply lost one of its inputs.
Typical cost: $120–$400
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
- Tell the technician which display-window code you see: 301 is an open circuit, 302 a short, and it saves them a step.
- Book a service call. There is no homeowner check on Noritz's list for this code.
Code 30 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: