Applies to: SENSEI SENSEI RX/CX Non-SENSEI
What you can safely check
- Turn off the hot water tap, then turn the heater off and back on at the controller.
- Check for a tripped breaker or loose plug if power keeps dropping.
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 03, Rinnai’s service steps cover:
- power supply and wiring
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 9. 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.