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Rinnai code 16 (high outgoing temperature): what to check

By How House Works EditorialBased on Rinnai manualsChecked against sources Updated

Rinnai display

16

“High Outgoing Temperature (safety shutdown because water heater is too hot)”

RU/RUR/RSC, RX, RE/REP, V, RL/VC · SENSEI RU Installation and Operation Manual, p. 74; SENSEI RUR Installation and Operation Manual, p. 73; SENSEI RSC Installation and Operation Manual, p. 73; SENSEI RX/CX Tech Sheet, p. 1; RE Series Installation and Operation Manual, p. 50; REP Series Installation and Operation Manual, p. 49; Value Series Installation and Operation Manual, p. 34; V53De Installation and Operation Manual, p. 29; VC Series Installation and Operation Manual, p. 37; Troubleshooting Tankless Water Heater Diagnostic Codes, p. 27
Owner checks, then technician

RE/REP tables: "High Outgoing Temperature" (RE manual, p. 50). Value, V53De and VC tables: "Over Temperature Warning (safety shutdown because unit is too hot)" (Value manual, p. 34). The troubleshooting guide defines it as outlet water above 203°F (95°C) (p. 27).

What it means

Code 16 is a safety shutdown. Rinnai’s troubleshooting guide defines it as outlet water temperature above 203°F (95°C) p. 27. The Value, V53De and VC tables call it an over temperature warning Value manual, p. 34.

The RU, RUR, RSC and RX tables list two remedies, both for parts inside the heater: confirm the fan motor works, and replace the gas valve assembly RU manual, p. 74; SENSEI RX/CX Tech Sheet, p. 1. These tables do not split remedies between owner and professional; in our reading, neither of the two is an owner task. The Non-SENSEI tables add air flow around the heater and vent terminal, short-cycling from low water flow in a circulating system, foreign material in the combustion chamber or exhaust piping, and blockage in the heat exchanger Value manual, p. 34; RE manual, p. 50.

Check these first

Rinnai’s tables warn that consumers should never attempt any action they are not qualified to perform RU manual, p. 73; Value manual, p. 34. The V53De manual adds: call a licensed professional for any remedy that involves gas or electricity, or if you have any doubt about doing it yourself V53De manual, p. 28. If you smell gas, the Value and V53De manuals put one step before those in the box above: leave the premises Value manual, p. 28; V53De manual, p. 22.

  1. Check for anything restricting air flow around the heater and the vent terminal Value manual, p. 34; RE manual, p. 50; VC manual, p. 37. On the outdoor V53De, check around the unit and its exhaust outlet V53De manual, p. 29.
  2. If the heater is overheating, turn off the manual gas control valve to it, by hand only RU manual, p. 8; Value manual, p. 3.
  3. Feel the water before a bath or shower. Rinnai warns that water above 125°F (52°C) can cause severe burns RU manual, p. 70 and tells users to check the water temperature before entering a shower or bath p. 7.
  4. Note the code history RU manual, p. 73 and call for service if 16 comes back.

The tables give no separate reset step for code 16.

When to call a licensed technician

  • The fan motor and the gas valve assembly RU manual, p. 74. The guide also has the technician check that the check valve behind the fan motor is not stuck troubleshooting guide, p. 27.
  • Low water flow in a circulating system that causes short-cycling Value manual, p. 34.
  • Foreign material in the combustion chamber or exhaust piping, and blockage in the heat exchanger Value manual, p. 34.
  • On RE and REP models, the thermistor sensor and scale build-up on it RE manual, p. 50.
  • The gas type setting, which must match the gas type on the rating plate troubleshooting guide, p. 27.

Notes for different models

The RE and REP tables use the shorter name “High Outgoing Temperature” RE manual, p. 50. On every series, a separate code, 14, covers the overheat safety on the heat exchanger or the thermal fuse RU manual, p. 73; RE manual, p. 50.

Related Rinnai codes

  • 14 “Heat Exchanger Overheat”
  • 61 “Combustion Fan”
  • 54 “High Exhaust Gas Temperature”

All Rinnai codes

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Sources

  1. Rinnai America Corporation. Troubleshooting Tankless Water Heater Diagnostic Codes. 100000652(03), 5/2024; for trained and qualified professionals. Accessed Oct 12, 2026.
  2. Rinnai America Corporation. SENSEI RU Installation and Operation Manual. 100000467(07), 1/2021; cover title: Tankless Water Heater (Residential) Installation and Operation Manual; listed on rinnai.us as N Series Residential Condensing Installation and Operation Manual. Accessed Oct 12, 2026.
  3. Rinnai America Corporation. SENSEI RUR Installation and Operation Manual. 100000508(07), 1/2021; cover title: Tankless Water Heater (With Pump) Installation and Operation Manual. Accessed Oct 12, 2026.
  4. Rinnai America Corporation. SENSEI RSC Installation and Operation Manual. 100000773(01), 1/2023. Accessed Oct 12, 2026.
  5. Rinnai America Corporation. SENSEI RX/CX Tech Sheet. 100000849, U362-0875(00); no printed date or page numbers (p. 1 is the PDF page). Accessed Oct 12, 2026.
  6. Rinnai America Corporation. RE Series Installation and Operation Manual. 100000722(03), 6/2022; cover title: Tankless Water Heater Installation and Operation Manual. Accessed Oct 12, 2026.
  7. Rinnai America Corporation. REP Series Installation and Operation Manual. 100000726(03), 3/2022; cover title: Tankless Water Heater (With Pump) Installation and Operation Manual. Accessed Oct 12, 2026.
  8. Rinnai America Corporation. Value Series Installation and Operation Manual. 100000258(10), 4/2021; cover title: Direct Vent Tankless Water Heater Installation and Operation Manual. Accessed Oct 12, 2026.
  9. Rinnai America Corporation. V53De Installation and Operation Manual. 100000561(05) (from the file name; no printed revision or date). Accessed Oct 12, 2026.
  10. Rinnai America Corporation. VC Series Installation and Operation Manual. 100000244(12), 8/2019; cover title: Direct Vent Tankless Water Heater Installation and Operation Manual. Accessed Oct 12, 2026.