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
The same code number can mean something different on another series — make sure you're reading the page for your exact unit: