Rinnai tankless water heater code 32
Your series decides which reading applies. Across the 4 Rinnai series documented here, code 32 is listed as outgoing water temperature thermistor fault (3 series) and heat exchanger outgoing temperature sensor fault (1 series). Find your series in the table below, where those readings route to a replacement part and a professional.
What code 32 means on each Rinnai series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| Non-SENSEI | Outgoing water temperature thermistor fault | Part replacement | $150–$450 |
| RH180 Hybrid | Heat exchanger outgoing temperature sensor fault | Call a pro | $150–$700 |
| SENSEI | Outgoing water temperature thermistor fault | Part replacement | $150–$450 |
| SENSEI RX | Outgoing water temperature thermistor fault | Part replacement | $150–$450 |
Each row opens the full page for that generation. We hold manuals for Non-SENSEI, RH180 Hybrid, SENSEI and SENSEI RX, and each one gets its own reading of code 32 — what Rinnai documents, what you can safely check yourself, and what the repair should cost.
What each manual actually says
The table above compares 4 series in four columns, which is enough to route you and not enough to explain anything. This is the Rinnai wording behind each row, one entry per manual, so you can see where the 4 readings of code 32 agree and where they part company.
Non-SENSEI — Outgoing water temperature thermistor fault
The sensor that reads the temperature of the water leaving the unit is out of range or not reporting. Rinnai's procedure is the standard thermistor one: check the harness, drain the unit, pull the sensor and clean any scale off it, then compare its resistance against the published curve — 11.4 to 14K ohms at 59°F, falling as it warms.
RH180 Hybrid — Heat exchanger outgoing temperature sensor fault
The sensor reading the water temperature leaving the heat exchanger is out of range. Rinnai's list has four steps: check the sensor wiring for damage, measure the sensor's resistance, clean scale build-up off the sensor, and replace it. The third one is the useful one — on this appliance Rinnai expects scale on the sensor itself to be a cause, not just a background condition.
SENSEI — 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.
SENSEI RX — Outgoing water temperature thermistor fault
The sensor that reads the temperature of the water leaving the heater is out of range or not reporting. Rinnai's checks are 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.
How much the answer changes between series
This is the part that catches people out. Code 32 does not lead to the same job on every Rinnai series: a replacement part and a professional are both documented answers to this number, depending on the generation. Buying a part because a page for a different series said so is how this fault gets expensive.
The spread is real money. On the Non-SENSEI the worst case is $450; on the RH180 Hybrid the same number can reach $700. That is a $250 gap behind one number.
Which Rinnai do you have?
On the 4 series that report code 32, the model number on the rating label starts C, RC, RU, RUC and RUR — match yours against the 78 listed below. You can also use the full model-number decoder.
Where this comes from
Source: Rinnai Troubleshooting Tankless Water Heater Diagnostic Codes (100000652) (p. 37), read Aug 2026 — the manufacturer's own documentation for this Rinnai range.
Source: Rinnai RH180 Operation and Installation Manual (100000319) (p. 36), read Sep 2026 — the manufacturer's own documentation for this Rinnai range.
The same number on other brands
Code 32 is not a standard across the industry — every manufacturer publishes its own table. If your unit is not a Rinnai, this number means something else entirely:
Parts, guides and symptoms behind code 32
Code 32 on these 4 Rinnai series points at 2 guides, 2 parts and 2 symptoms, each named by the manufacturer's own procedure for this code.