Rheem Tankless Gas Code 32
Heat exchanger thermistor malfunction. The sensor mounted on the heat exchanger is not reporting correctly. Rheem's diagnostic is a resistance measurement at connector R on the control board, which differs between mid- and high-efficiency units.
Part replacementThe verdict
Replace a part
A sensor fault, not an exchanger fault — worth saying, because the code name frightens people into pricing a heat exchanger. The part is cheap; the visit is most of the cost.
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 Tankless Gas — not averaged across the brand.
Source: Rheem Tankless Gas Troubleshooting Pocket Manual (SVC820) (p. 60), read Aug 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
- Note when the unit was last flushed and whether your water is hard.
- Book a service call.
Frequently asked questions
Does code 32 mean my heat exchanger is failing?
No. It is the sensor attached to it. A failing heat exchanger shows up as overheat codes or as leaking, not as a thermistor code.
Don't confuse this with
4 other Rheem Tankless Gas 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: