What does error code 16 mean on a Rinnai tankless water heater?

High outgoing water temperature. A safety shutdown because the outlet water temperature exceeded 203°F (95°C).

Can I fix Rinnai code 16 myself?

Start with these safe checks: Turn the heater off and check outside that the vent terminal isn't blocked. Rinnai's next steps include fan and gas valve replacement. Call a qualified technician.

When should I call a technician for code 16?

Rinnai's next steps include fan and gas valve replacement. Call a qualified technician. Smell gas? Leave right away, don't touch light switches or phones inside, and call your gas utility or 911 from outside. Never open a gas valve, burner, gas line, vent or flue connection, or bypass a safety switch. Repeated lockouts, scorching, soot, or a CO alarm mean shut it off and call a licensed gas technician.

Rinnai Tankless Water Heater Error Code 16: High outgoing water…

What 16 means

A safety shutdown because the outlet water temperature exceeded 203°F (95°C).

Likely causes

Air flow restriction at the vent terminal
Fan or gas valve problem
Heat exchanger blockage

Safe first checks

Turn the heater off and check outside that the vent terminal isn't blocked.

When to stop

Rinnai's next steps include fan and gas valve replacement. Call a qualified technician.

Checked against: Rinnai: Troubleshooting Tankless Water Heater Diagnostic Codes (100000652). Codes can differ by model and year, so confirm with your owner's manual.