Rinnai Error Code 31: Inlet Thermistor Failure
Warning: Your Rinnai water heater is locked out and needs professional attention to prevent water supply interruption.
How to Fix Rinnai Code 31
- Check if the water heater is receiving power. If not, reset the GFCI outlet or replace the fuse.
- If the water heater has power, do not attempt to fix the issue yourself. Contact a professional HVAC technician.
How to Reset Rinnai Code 31
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
What does 31 mean?
Rinnai's error code 31, Inlet Thermistor Failure, indicates a problem with the sensor that measures the temperature of the incoming water. This sensor helps regulate the water heater's operation and ensure safety. If it malfunctions, the water heater will shut down to prevent overheating or freezing, displaying error code 31 on the digital display.
Affected Models
Replacement Parts
| Part | OEM Number | Est. Cost |
|---|---|---|
| Inlet Thermistor | RIN-12010100 | — |
| Control Board | RIN-12020000 | — |
Related Codes on Same Models
| Code | Description | Severity |
|---|---|---|
| 02 | Stagnant Water Detection | Warning |
| 10 | Air Supply/Exhaust Blockage | Warning |
| 11 | No Ignition | Warning |
| 12 | Flame Failure | Warning |
| 14 | Thermal Fuse | Warning |
| 16 | Over-Temperature | Warning |
| 19 | Electrical Grounding | Warning |
| 25 | Condensate Overflow | Warning |
| 29 | Condensate Neutralizer | Warning |
| 32 | Outlet Thermistor Failure | Warning |