Applies to: SENSEI SENSEI RX/CX Non-SENSEI
What you can safely check
- Stop using hot water and turn the heater off. Call a technician.
- If your heater has a maintenance history of scale, mention it – scale is a common contributor.
What a technician will look at
Everything past the checks above involves gas pressure, live electrical parts or opening the sealed cabinet. That work is for a licensed gas or plumbing professional. For code 16, Rinnai’s service steps cover:
- heat exchanger scale
- outlet thermistor
- flow sensor and gas valve
Smell gas? Don’t touch switches or try to reset the heater. Leave the building and call your gas supplier or 911 from outside.
Source: Rinnai, Troubleshooting Tankless Water Heater Diagnostic Codes (document 100000652), page 27. The code name is Rinnai’s; the explanation is ours. Codes differ between series – check the model on your heater’s rating plate. This site is independent and not affiliated with Rinnai.