Rinnai Non-SENSEI Code 19
Electrical grounding fault. An electrical fault in the heater's DC circuit. Rinnai's note is specific and useful: a code 19 that appears the moment water starts flowing, with no flame visible in the burner box, means a short in one of the unit's components — a wiring harness, the water flow control or bypass valve, or anything else on that circuit. The technician's method is to unplug one component at a time until the unit will cycle.
Call a proThe verdict
Call a licensed plumber
An electrical fault inside a gas appliance. The diagnosis is a process of elimination inside the cabinet with the covers off, which is not homeowner work.
Typical cost: $150–$800
US estimate for parts and labor. Prices vary by region and by who does the work — see how we estimate costs.
What the manual says
The meaning above is transcribed from the manufacturer's diagnostic documentation for the Non-SENSEI — not averaged across the brand.
Source: Rinnai Troubleshooting Tankless Water Heater Diagnostic Codes (100000652) (p. 31), read Aug 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
Before anything else: if you smell gas, stop here, leave, and call your gas utility.
- Note whether the code appears the instant you open a hot tap or only after the unit has been running — Rinnai treats those as different starting points.
- Check whether anything was worked on recently near the unit; a disturbed harness is a common trigger.
- Book a licensed professional.
Code 19 on other Rinnai series
Other Rinnai series report code 19 under the same fault name, but each manual is transcribed separately and they do not read alike: