Rinnai SENSEI Code 32
Outgoing water temperature thermistor fault. The sensor reading the temperature of water leaving the heater is out of range or not reporting. Rinnai's sequence is the wiring back to the PC board, then scale build-up on the thermistor itself, then its resistance against a published table — around 11.4-14K ohms at 59°F falling to 2.2-2.7K ohms at 140°F.
Part replacementThe verdict
Replace a part
A sensor, not a combustion fault, and one of the cheaper repairs on the unit. Rinnai's step before condemning it is to remove it and clean off scale, so on hard water a flush plus a clean can be the whole fix. Reaching it needs the water isolated and the unit drained.
Typical cost: $150–$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 SENSEI — not averaged across the brand.
Source: Rinnai Troubleshooting Tankless Water Heater Diagnostic Codes (100000652) (p. 37), read Aug 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
- Note whether your water is hard and when the unit was last flushed — Rinnai checks the sensor for scale before replacing it.
- Book a service call; the water has to be isolated and the unit drained.
Frequently asked questions
I have an RUR model and a crossover recirculation setup.
Then there is an extra step on this code. Rinnai has a specific check for RUR199 and RUR160 models in crossover mode: isolate the unit, replace the bypass filter with the bypass plug, and if that fixes it, inspect the check valve between the internal circulation pipe and the circular joint connection.
Code 32 on other Rinnai 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
2 other Rinnai SENSEI 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: