DIY Error Codes

Rinnai Tankless water heater Code 16

Safety shutdown: outlet water temperature exceeded 203 °F (95 °C).

This is an overheat safety shutdown. Check outside for blocked air flow at the vent terminal, then call a pro.

Start the fix →When to call a pro ↓
Full answer & models

Rinnai code 16 means: High Outgoing Water Temperature. This is an overheat safety shutdown. Check outside for blocked air flow at the vent terminal, then call a pro.

Applies to: SENSEI™ SeriesNon-SENSEI™ Series
Also searched as: Rinnai code 16, Rinnai error 16, Rinnai error code 16

Burn risk: outlet water exceeded 203 °F (95 °C). Keep away from hot taps. If you smell gas, leave and call your gas supplier from a neighbor's phone.
Why
If you smell gas: do not try to light any appliance, do not touch any electrical switch, and do not use any phone in your building. Leave and call your gas supplier from a neighbor's phone; if you cannot reach them, call the fire department. Rinnai states that only trained and qualified professionals may follow its diagnostic-code service instructions, and that power, gas and water must be turned off before servicing. Never operate the heater with any vent pipe disconnected. Do not adjust the internal gas valve. Burn hazard (Rinnai): hot exhaust and vent may cause serious burns; keep small children and animals away, and hot water outlet pipes can be hot to touch.

What 16 means

Safety shutdown: outlet water temperature exceeded 203 °F (95 °C).

More detail
Rinnai's diagnostic-code guide (page 25) titles code 16 "High Outgoing Water Temperature". Rinnai describes it as a safety shutdown when outlet water temperature exceeds 203 °F (95 °C). Rinnai's guide is written for trained, qualified professionals, so this page lists only the owner-level checks and tells you when to stop.

5-minute checks

Fix it step by step

Step 1 of 2

  1. Check air flow around the vent terminal

    • 5 min
    • None
    • DIY

    Safety: Burn risk: outlet water exceeded 203 °F (95 °C). Keep away from hot taps. If you smell gas, leave and call your gas supplier from a neighbor's phone.

    Outside only. Do not disconnect vent pipe.

    More detail

    Check air flow around the vent terminal.

    Rinnai's guide, code 16 step 1: check for restrictions in air flow around the vent terminal.

    Did the code clear?

  2. Call a licensed pro

    • Decision
    • None
    • Pro decision

    Stop here and book a qualified technician.

    More detail

    Call a licensed pro.

    Rinnai's other code 16 steps (fan, check valve, combustion chamber, heat exchanger, gas type, gas valve) are for qualified professionals.

    Still showing 16?Need a pro → call a pro

Code cleared. Nice work.

Watch the display for a day to make sure it stays clear.

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Fixed after any step? Watch the display for a day to make sure it stays clear. Still 16 after step 2? call a pro.

Call a pro if…

  • Any time code 16 appears more than once: it is an overheat safety shutdown.
  • Water at fixtures is unusually hot.

FAQ

What does Rinnai code 16 mean?

High outgoing water temperature: a safety shutdown when outlet water exceeds 203 °F (95 °C), per Rinnai's guide.

Source: Rinnai, Troubleshooting Tankless Water Heater Diagnostic Codes (100000652), page 25. Written by the DIY Error Codes team. Updated 2026-10-16. DIY Error Codes is independent and not affiliated with or endorsed by Rinnai.